Japanese Traffic Rules

The traffic rules that come up most in the written test, organised by topic. Road signs have their own page.

Speed & stopping distance

Legal speed limits by road and vehicle type, and the two components of stopping distance.

  • Stopping distance = reaction distance (how far you travel before braking starts) + braking distance (from brakes engaging to a full stop). Knowing this split is the whole point of many questions.
  • Both braking distance and centrifugal force scale with the SQUARE of speed — double the speed means roughly 4x the distance or force, not 2x.
  • Default limits: 60 km/h for cars on ordinary roads, 30 km/h for mopeds. A moped can never legally exceed 30 km/h even if a sign posts a higher limit.
  • A legal minimum speed (50 km/h) exists only on the main carriageway of expressways — never on ordinary roads.
  • "Under the speed limit is always safe" is false — rain, night, and traffic density all call for slowing further below the posted limit.
  • A wet road or worn tyres can roughly double your braking distance compared with dry pavement.

Intersections

How to turn right and left at intersections, right-of-way at uncontrolled intersections, roundabouts, and giving way to emergency vehicles.

  • Right turn: move toward the centre line first, then turn just inside the intersection's centre point, slowly. Left turn: move to the left edge first, then hug the corner. Mixing these two up is the most common trap.
  • At an uncontrolled intersection of similar-width roads, yield to traffic from the LEFT — but this flips regardless of direction if the other road is a priority road or clearly wider.
  • Roundabouts follow different rules entirely: always slow down on entry, traffic already circulating always has priority, and you only signal when exiting, not entering.
  • Straight-ahead and left-turning traffic always has priority over a car turning right — entering the intersection first does not grant right-of-way.
  • Signal timing: ~3 seconds before for a lane change, 30 metres before for a turn or U-turn.
  • Even on a priority road or with a green light, you still must drive at a safe speed appropriate to the intersection's conditions — priority doesn't remove that duty.

Overtaking

The legal distinction between overtaking (changing lanes to get ahead) and passing (not changing lanes), and where overtaking is banned.

  • Overtaking = changing lane to get ahead of the car in front; passing (追い抜き) = getting ahead without changing lane. The ban only applies to overtaking, so this distinction flips many answers.
  • The "30 metres before" rule applies to intersections, railway crossings, and pedestrian/cycle crossings — a different number from the 5m/10m no-parking rules, so don't mix them up.
  • Overtaking on the right is the default. You only pass on the left when the car ahead has pulled toward the centre (or right edge on a one-way street) to turn right.
  • Overtaking is banned near the top of an uphill slope and on a steep downhill — but NOT on a steep uphill slope itself, a common trap.
  • Blind corners are overtaking-banned regardless of how good visibility actually is at the time.
  • Even within 30m before an intersection, overtaking isn't banned if you're on the priority road through that intersection — it's not banned at "every" intersection.

Parking & stopping

The distances within which parking and stopping are banned near specific locations, and the legal difference between "parking" and "stopping."

  • The most-tested pair: 5m applies to intersections, corners, pedestrian crossings (front and back), fire hydrants, fire alarms, construction site edges, and facility entrances; 10m applies to railway crossings (front and back), safety zones (front and back), and bus stop posts.
  • "Stopping" (停車) is brief — e.g. letting a passenger out — and is allowed even where parking is banned. "Parking" (駐車) is loading/unloading over 5 minutes, or the driver being unable to move the car immediately. Whether you can move immediately matters more than the clock.
  • Both parking AND stopping are banned at intersections, crossings, railway crossings, tunnels, and steep grades/hilltops. Only PARKING (not stopping) is banned near fire hydrants, fire alarms, construction sites, and facility entrances.
  • Grade-related parking bans apply to both uphill and downhill "hilltop / steep grade" — a slightly different scope from the slow-down and overtaking rules, which only cover a hilltop or a steep downhill.
  • Pedestrian crossings ban parking/stopping within 5m front AND back, railway crossings within 10m front AND back — don't confuse this with overtaking's "30m before only" rule.
  • Parking is generally banned wherever it would leave less than 3.5m of clearance on the right side of the car (with exceptions like loading where the driver can move immediately).

Protecting pedestrians

A driver's duties toward pedestrians at crossings, safety zones, and around vulnerable road users like school buses.

  • Approaching a crossing: if it's unclear whether anyone will cross, slow to a speed you can stop at instantly. If someone is crossing or about to cross, you must actually stop and yield — slowing down is not enough in that case.
  • Passing a car stopped before a crosswalk: you must also come to a full stop before pulling past it, since a pedestrian could be hidden in its blind spot — slowing down again is not enough.
  • You only need to slow down near a safety zone if a pedestrian is actually standing in it — no obligation if it's empty.
  • Splashing mud or water on pedestrians is itself a traffic violation, not just bad manners.
  • White/yellow cane users and children boarding/leaving a school bus require you to stop or slow down — maintaining speed is not an option.
  • Vehicles permitted onto a pedestrian-only road (e.g. residents with a garage there) must still slow down and watch for pedestrians.

Slowing & stopping

Where slowing down (徐行) is legally required versus where a full stop is required, and the correct procedure for crossing railway tracks.

  • The legal definition of 徐行 is "a speed at which you can stop immediately" — roughly 10 km/h or under. It means "able to stop instantly," not just "driving slowly."
  • Slowing down is required at: blind intersections (unless signal-controlled or you're on the priority road), corners, hilltops, and steep downhills. A corner requires slowing regardless of visibility.
  • Railway crossings require a full stop just before them, always — unless a working signal is showing green, in which case you may proceed without stopping (but must still check for trains). A raised barrier is not a reason to skip stopping.
  • Slow-down zones cover "the top of an uphill" and "a steep downhill" — a steep uphill by itself is not included.
  • A stop sign requires a full stop at the stop line regardless of how good visibility is — slowing down never substitutes for stopping.
  • The duty doesn't end once you've stopped — you must also not obstruct cross traffic afterward.

How to drive on the road

Lane discipline, signal timing, headlight rules, one-way streets, and priority/dedicated bus lanes.

  • Signal timing cheat sheet: lane change ≈ 3 seconds before, turn/U-turn = 30 metres before, starting off = "when about to start" (no fixed distance). Mixing up the 3-second and 30-metre rules is a classic trap.
  • With 3 or more lanes in your direction, keep to the leftmost lanes — the rightmost lane stays clear for overtaking.
  • A "priority" bus lane can be used by ordinary cars (yield when a bus approaches); a "dedicated" bus lane generally cannot be used at all — similar names, different rules.
  • For an approaching emergency vehicle, a full stop is only required at or near an intersection — elsewhere you just need to move left and yield.
  • Headlights are required at night regardless of street lighting — a well-lit area is not an exemption.
  • One-way streets are the one case where driving on the right half of the road is explicitly allowed.

Driver's responsibilities

A driver's personal obligations — drink-driving, seatbelts/child seats, novice/elderly/disability markings, and carrying your licence.

  • Drink-driving is banned regardless of amount. It also implicates anyone who offered the drink, lent the car knowing the driver had been drinking, or rode along knowing it — 4 separate parties can be held responsible, not just the driver.
  • Displaying the novice-driver mark (first year of a licence) is a legal requirement. Displaying the elderly-driver mark (age 70+) is only a "best-effort" obligation — this distinction between "required" and "should try to" is frequently tested.
  • Children under 6 legally require a child seat — being held in an adult's arms is never an accepted substitute.
  • Forgetting your licence at home isn't "driving without a licence," but it is a separate "failure to carry" violation.
  • Holding a phone to talk while driving is banned; using it after you have safely stopped the car is fine.
  • Fatigue's effects usually show up in vision first — missed hazards and slower detection — before you necessarily "feel" tired.

How a vehicle behaves

A vehicle's physical behaviour — the inside-wheel gap on turns, centrifugal force, centre of gravity, AT creep, and headlight/braking etiquette.

  • The inside-wheel gap (内輪差, the rear wheels tracking inside the front wheels on a turn) grows with wheelbase — bigger vehicles create a bigger gap, a major cause of left-turn accidents involving cyclists or pedestrians.
  • Centrifugal force and collision force both scale with the SQUARE of speed. Double the speed means roughly 4x the force — a higher centre of gravity (e.g. a high load) also raises rollover risk.
  • Automatic-transmission cars can creep forward on idle alone (creep phenomenon) — keep the brake pressed while stationary, and confirm P or N before starting the engine.
  • Use engine braking on long descents rather than relying only on the foot brake, which can fade or vapour-lock from overuse.
  • A motorcycle's brakes should be applied on both wheels together — using only the front brake heavily is a mistake.
  • Switch to low-beam headlights whenever passing oncoming traffic at night.

Expressways

Expressway-specific speed limits, shoulder and main-carriageway rules, merging technique, and breakdown procedure.

  • Main carriageway limits: 100 km/h default for ordinary cars (up to 120 km/h where posted), with a 50 km/h MINIMUM — this minimum-speed rule exists only on expressways, nowhere else.
  • Merge by accelerating in the acceleration lane to match the speed of main-carriageway traffic, not by slowing down or hesitating — a timid merge is more dangerous.
  • U-turns, reversing, and crossing the median on the main carriageway are always banned, even if you missed your exit — continue to the next one.
  • The shoulder (路肩) can never be driven on, even during a traffic jam — it must stay clear for breakdowns and emergency vehicles.
  • If you break down, use hazard lights plus a warning triangle/flare placed behind the car, then evacuate everyone outside the guardrail rather than waiting inside.
  • Tyre pressure should be set slightly HIGHER than normal for sustained high-speed driving, to prevent standing-wave tyre failure — lowering it is the wrong answer.

Accidents & first aid

The mandatory sequence of actions after a crash, basic first-aid facts, and the legal responsibilities that follow an accident.

  • The fixed order after any accident: stop driving → give first aid to the injured → secure the scene against further danger → THEN report to police. Reporting first, or skipping it, are both wrong.
  • Reporting to police is mandatory even for a property-only accident with no injuries, and even if both parties privately settle — skipping it is itself a violation, and also blocks any insurance claim.
  • CPR chest compressions: about 100–120 per minute, pressing down about 5cm — not a slow pace.
  • AEDs can be used by anyone, with no medical qualification required — don't hesitate.
  • Don't move an injured person unless staying in place is itself dangerous (e.g. risk of being hit again) — head and spine injuries are the main reason not to move someone by default.
  • Compulsory insurance (自賠責) is mandatory for both cars and mopeds with no exemption, but it only covers injury to others — voluntary insurance still matters for everything else.

Checks & maintenance

The difference between daily inspections, periodic inspections, and shaken (vehicle inspection), plus responsibility for a poorly maintained vehicle.

  • A private passenger car's "daily inspection" isn't on a fixed calendar — it's done at an appropriate time based on mileage and condition. Periodic inspection is yearly; shaken is every 3 years for a new car, then every 2.
  • Tyre tread below 1.6mm is illegal to drive on — 0.8mm is a trap number, not the real threshold.
  • Brake pedal free play needs to be within the correct range — none at all is also a defect (causes dragging and overheating), not just too much play.
  • Driving with defective equipment is banned regardless of whether the driver personally feels capable of handling it — the vehicle's owner/operator can also be held responsible, not just the driver.
  • Tyre pressure should match the manufacturer's specified value — too high and too low both cause problems; higher is not simply more efficient.
  • Open a radiator cap only once the engine has cooled — opening it hot can spray scalding water and steam.

Loads & towing

Size and weight limits for cargo, the signage required for overhanging loads, and how to rope-tow a broken-down car.

  • Cargo height limit: 3.8m from the ground (up to 4.1m on designated roads) — always measured from the ground, not the truck bed. Length can extend to 1.1x the vehicle's length, width to 1.2x — don't swap which ratio applies to which dimension.
  • Rope-towing a broken-down car needs no special towing licence, but you do need a licence valid for the towed vehicle itself. Keep the vehicles within 5m of each other, with a white cloth of at least 0.3m² at the rope's midpoint.
  • For seating-capacity purposes, children under 12 count as 2 children = 1 adult.
  • Exceeding the rated load capacity is banned outright, with no "just a short distance" exception — exceeding the size/weight limits requires prior permission from the police chief at the departure point.
  • An overhanging load needs a red cloth of at least 0.3m² by day, or a red light/reflector by night.
  • A standard motorcycle carrier can overhang up to 0.3m at the rear and 0.15m on each side.

Motorcycles

Motorcycle-specific braking technique, cornering method, helmet requirements, and how motorcycles appear to other drivers.

  • Brake with both wheels together as the default — front slightly stronger on dry roads, rear slightly stronger on slippery ones. Using only the front brake heavily is dangerous.
  • Finish slowing down BEFORE a curve, then lean the bike (rather than turning the handlebars) and hold a steady speed through the turn. Braking mid-curve tends to stand the bike up and carry it wide.
  • To other drivers, a motorcycle looks farther away and slower than it really is — a major cause of right-turn collisions where an oncoming car misjudges the gap.
  • The chin strap must always be fastened — an unfastened helmet comes off at exactly the moment it was needed, on impact.
  • There is no "short distance" exception to helmet use for any two-wheeled vehicle, mopeds included.
  • Weaving between stopped or slow-moving cars in traffic is dangerous, not a legitimate shortcut.

Bad conditions

Adjusting your driving for night, rain, fog, and snow/ice — the situations where visibility or grip drops.

  • In fog or facing oncoming glare, use LOW beam headlights — high beams reflect back off fog or rain and reduce visibility rather than improving it.
  • On snow, staying IN the existing tyre ruts grips better than fresh snow — leaving the ruts, not staying in them, is what causes skids.
  • Hydroplaning (a water film that kills steering/braking grip) and brake fade/vapour lock (from overusing the brake on a long descent) are two separate hazards with two separate fixes: slow down with good tread, versus use engine braking.
  • "Evaporation phenomenon": a pedestrian caught between your headlights and an oncoming car's headlights can become invisible — treat that zone as if someone might be there, especially while passing.
  • Bridges, tunnel entrances/exits, and shaded spots freeze first, even when the rest of the road looks dry — slow down there regardless of appearances.
  • Tyre chains go on the drive wheels — front-wheel drive gets front chains, rear-wheel drive gets rear chains.

Driving psychology & physics

How speed, fatigue, and attitude affect perception, judgement, and reaction time — plus the legal ban on phone use while driving.

  • Fatigue, drowsiness, and distraction all lengthen the REACTION distance (空走距離) — the distance before braking even starts — not the braking distance itself.
  • Higher speed narrows your field of view and pulls focus toward the distance, making nearby hazards easier to miss, not easier to see.
  • Believing you're a skilled driver doesn't cancel physics — overconfidence is itself a leading cause of accidents from unsafe overtaking.
  • Holding a phone to talk while driving is banned outright; even hands-free setups still ban looking at the screen while driving.
  • Your seating position and posture genuinely change your blind spots — adjusting your seat correctly before driving is a real safety step, not just comfort.
  • Never stare directly at oncoming glare — shift your eyes to the left edge of your own lane instead, and slow down if the glare is strong.