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Safe driving duties

This topic checks the basic duties of a driver: no alcohol, no phone in hand, seat belts and child seats, and being fit to drive. Japan enforces these strictly, and the penalties are heavy.

Key rules

Do not drive after drinking alcohol, or under the influence of drugs such as stimulants or thinner. Alcohol from the night before can still affect you the next morning.
Driving with breath alcohol of 0.15 mg/L or more is 酒気帯び運転. Driving after drinking is prohibited by law even below 0.15 mg/L.
Driving with breath alcohol of 0.5 mg/L or more is 酒酔い運転 (this number was added to the law on 2026-07-21). It is also 酒酔い運転 below 0.5 mg/L if alcohol may stop you from driving normally.
Do not lend a vehicle to a drinker, serve alcohol to a person who will drive, or ride with a driver you know has been drinking. These people are also punished.
Do not use a mobile phone in your hand or stare at a phone or car-navigation screen while driving. The ban does not apply when the vehicle is stopped.
The driver must wear the seat belt and make every passenger wear one, in the front and the back seat, even if the car has airbags. Exceptions are for illness or other unavoidable reasons.
An infant (a child under 6) must be put in a child seat that fits the child's growth. Unavoidable reasons such as illness are the exception.
Do not drive when overtired or ill. Take a rest at least once every 2 hours on a long drive, and stop and rest when you feel sleepy. Do not drive after taking cold or headache medicine that makes you sleepy.
Obstructive driving (あおり運転), such as sudden braking, not keeping a safe following distance or banned lane changes done to obstruct another vehicle, is a crime. It can lead to licence revocation.

Numbers to remember

0.15 mg/LBreath alcohol level for 酒気帯び運転 (up to 3 years in prison or a fine up to 500,000 yen). At 0.25 mg/L or more the licence is revoked.

0.5 mg/LBreath alcohol level for 酒酔い運転 since 2026-07-21 (up to 5 years in prison or a fine up to 1,000,000 yen).

2 hoursTake a rest at least once every 2 hours on a long drive.

Under 6Age of an infant who must use a child seat.

3 pointsBase points for holding a phone while driving a car (6 points if it causes danger).

5 yearsMaximum prison term for obstructive driving that causes serious danger (3 years for obstructive driving itself).

Common traps

'Below 0.15 mg/L is allowed.' Wrong: 0.15 mg/L is the level for the penalty and points, but driving after drinking is banned at any level.
'Seat belts are needed only in the front seats or only on expressways.' Wrong: all seats, on all roads.
'Only the driver is punished for drunk driving.' Wrong: people who lend the car, serve alcohol or ride along are punished too.
'The seat belt is not needed with airbags' or 'never any exception.' Both are wrong: airbags do not replace the belt, but illness and other unavoidable reasons are exceptions.
'You may hold a phone for a short call while driving.' Wrong: only a stopped vehicle is outside the ban.

In Japan, driving after any amount of alcohol is illegal, and the penalties also reach people who lend a car, serve drinks or ride along. Seat belts are required in every seat on every road.

Try 2 questions

When a child under 6 rides in your car, you must have the child use a child seat suited to the child's stage of growth, unless there is an unavoidable reason such as illness.

If a parent or guardian holds the young child in their arms, the child does not need to use a child seat.

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