Daihō Castle (大宝城, Daihō jō) was a hirayama-style Muromachi period Japanese castle located in what is now the city of Shimotsuma, Ibaraki Prefecture, in the northern Kantō region of Japan.

[1] Daihō Castle is located at the northern end of a cape-shaped plateau surrounded by paddy fields.

Since 1981, archaeological excavations have been carried out to confirm the remains of the site, which is currently occupied by the Daihō Hachiman-gu, a Shinto shrine.

The castle site is about 5 minutes on foot from Daihō Station on the Kantō Railway’s Jōsō Line.

After Southern Court general Kitabatake Chikafusa was defeated at Oda Castle, he sought shelter at Daihō Castle and recognized the Shimotsuma clan as shugo of Hitachi Province before escaping to Yoshino.