The Kōshū Kaidō (甲州街道) was one of the five routes of the Edo period. It was built to connect Edo (modern-day Tokyo) with Kai Province in modern-day Yamanashi Prefecture, Japan. The route continues from there to connect with the Nakasendō's Shimosuwa-shuku in Nagano Prefecture. Many feudal lords from Shinano Province made use of the road during sankin-kōtai, including those from the Takatō, Suwa and Iida domains.

The Kōshū Kaidō's route is followed closely by the modern Route 20.

There are 44 post stations along the Kōshū Kaidō. (per Wikipedia)