Information
- The URL of Japan Standard Time in large letters has been changed, so please be careful when you use it.
The new URL is as follows.
https://www.nict.go.jp/JST/JST6_E/ (2024/4/22) - No leap second will be introduced on January 1, 2026. (2025/7/8)
（No leap second was introduced on July 1, 2025.） - The Time Dissemination by Telephone (TEL-JJY) ended on March 31, 2024. (2024/4/1)
- As previously announced, we have completed updating the servers used for public NTP services, so all public NTP servers no longer support NTP version 1. Therefore, if you are using NTP version 1, please migrate to NTP version 2 or later. (2024/3/14)
- "Telephone JJY" will be completely replaced with "Hikari Telephone JJY" on April 1, 2024. (2024/1/4)
- Japan standard time distribution service over analog telephone lines (Telephone JJY) ends March 31, 2024. (2023/3/15)
Topics
- Press Release： JJY transmission recognized as IEEE Milestone!
The Standard Time and Frequency Signal is a historic achievement that has contributed to the development of Japan’s society and industry for more than 80 years.（2025/11/25） - Press Release： World's first use of the "Optical lattice clock" to maintain National standard time.
〜Synchronization with UTC became possible only with the clock of NICT〜（2022/6/10）
LF Standard Time and Frequency Transmission Station
- Periodic maintenance of facilities in the LF Standard Time and Frequency Transmission Stations will be performed. (Links to a Japanese page) (2025/8/8)
- Transmission Information of JJY signals (Japanese version only)
- Operation Information of LF stations (Japanese version only)
Contents
Welcome to Japan Standard Time (JST) Group. JST Group plays an important role in the Generation, Comparison, and Dissemination of Japan Standard Time and Frequency standard. Please choose the contents you'd like to use.
Contact Us
Please contact us if you have any questions, comments, corrections, or suggestions.