Reidai Bridge, Stone arch footbridge in Misato, Kumamoto, Japan

Reidai Bridge is a single-arch stone bridge over the Midorikawa River in Misato, Kumamoto Prefecture. Its arch span of 28.3 m is the largest among Japanese stone bridges completed before the Meiji era. The bridge is 89.86 m long, 5.45 m wide and 16.32 m high, built of rough grey-brown masonry blocks with a low stone parapet and a protruding band outlining the arch ring.

A wooden bridge stood here from 1819 but was repeatedly washed away, so the shōya Shinohara Zenbei proposed a stone span and helped fund it. The stonemasons Urasuke, Uichi and Takehachi with carpenter Bannana began work in 1846 and finished in 1847, in only six or seven months. It became a National Important Cultural Property on 15 June 1967 and was restored to its original form from 1980.

The name Reidai comes from a passage in the Chinese classic Mencius about King Wen's Lingtai, or observation tower; Shinohara Zenbei chose it because villagers finished the work ahead of schedule. The bridge is also called Funatsu Bridge, after the Funatsu gorge it spans.

The bridge stands on National Route 218 in Misato, Kumamoto, with parking for about ten cars, toilets, a shop and an observation point nearby. A private rest house sits across the road from the car park. From Kumamoto Sakura-machi bus terminal take the Kumamoto Bus bound for Tomochi, get off at the terminus Tomochi Gakko-mae, then walk 30 minutes (2.5 km).

The bridge's name comes from a passage in Mencius about King Wen's Lingtai terrace: Shinohara Zenbei, who funded the project, saw the villagers' swift collective effort as a parallel to that ancient story. The 1847 build took only six to seven months, with 72 carpenters and 43,967 person-days of labour.