Minimum speedJapan
6. Minimum speed
A minimum speed is the lowest speed that vehicles are required to maintain on a particular road or under specified conditions. Minimum-speed rules are intended to prevent vehicles travelling unnecessarily slowly from disrupting traffic or creating large speed differences between road users.
A minimum speed does not require drivers to maintain that speed when traffic, weather, visibility, road conditions or safety require them to slow down. The way minimum speeds are indicated and enforced varies between countries.
Wikimedia.org • Oka21000 • CC BY-SA
What is Japan’s default minimum on a national expressway main carriageway?
On the qualifying main carriageway of a national expressway, the statutory minimum is 50 km/h where no minimum is designated by signs or markings. The statutory scope excludes specified carriageways; do not apply this automatically to every road called an expressway.
🔗 laws.e-gov.go.jp • Japan Road Traffic Act — Article 75-4; decree Article 27-3
🔗 laws.e-gov.go.jp • e-Gov — current enforced Road Traffic Act, revision metadata and full text
🔗 laws.e-gov.go.jp • e-Gov — current enforced decree revision metadata
Start of a minimum speed.
English • Traffic sign 324 • Minimum speed: 50 km/h. Sets the minimum for motor vehicles. It does not require maintaining that speed when safety demands otherwise.
日本語 • 324 • 最低速度:50 km/h。 自動車の最低速度を時速50キロメートルに指定しています。安全上必要な場合にも無理に速度を維持するという意味ではありません。
Sources
🔗 Commons.wikimedia.org
🔗 Laws.e-gov.go.jp • 道路標識、区画線及び道路標示に関する命令、別表第一・第二
🔗 Mlit.go.jp • 国土交通省、道路標識一覧
🔗 Npa.go.jp • 警察庁、交通規制基準(令和8年3月16日改正)、PDF 137ページ
SVG source: Monaneko • Public domain • Original revision 2013-08-19. Wikimedia original unmodified.
What is Japan’s official term for minimum speed?
The official wording is 最低速度. Signs or markings can designate a minimum for the relevant road. Read it separately from the maximum-speed restriction; the two numbers serve different purposes.
🔗 laws.e-gov.go.jp • Japan Road Traffic Act — Article 75-4; decree Article 27-3
🔗 laws.e-gov.go.jp • e-Gov — current enforced Road Traffic Act, revision metadata and full text
🔗 laws.e-gov.go.jp • e-Gov — current enforced decree revision metadata
Can a Japanese expressway driver go below the minimum to avoid danger?
Yes. The Act recognises slowing required by another legal rule and cases where it is unavoidable to prevent danger. A minimum does not require maintaining 50 km/h into congestion or another hazard.
🔗 laws.e-gov.go.jp • Japan Road Traffic Act — Article 75-4; decree Article 27-3
🔗 laws.e-gov.go.jp • e-Gov — current enforced Road Traffic Act, revision metadata and full text
🔗 laws.e-gov.go.jp • e-Gov — current enforced decree revision metadata

Traffic rules
Japan