Hachinohe Castle, Japanese castle ruins in Hachinohe, Japan

Hachinohe Castle was a hilltop fort in central Hachinohe with two concentric moats and a two-story central building with barracks but no donjon. Its inner bailey measured about 150 by 200 meters and held the palace; the second bailey, southeast of it, contained a martial arts school, stables and several shrines. The site is now Sanpachi Park, where earthen walls and moat traces remain.

The Nambu clan built this fort in 1627 to serve as their domain's headquarters. The site remained active until the Meiji Restoration ended the clan system in 1871.

The castle site is now Sanpachi Castle Park, with the Sanpachi Castle Shrine (Miyagi Jinja) founded in 1871 in the main bailey. The shrine's name comes from the three-eight (sanpachi) reading of the characters for Hachinohe. The Sumigoten Omote Gate, built in 1797, survives as the gate of the Nambu clan descendants' residence and is an Aomori Prefecture Important Cultural Property.

The park is accessible from Honhachinohe Station by a short uphill walk through stairs, taking roughly five minutes. Wear sturdy shoes for the climb, as the path is steep in places.

The 1797 Sumigoten Omote Gate, also called the Old Cherry Gate, survived the 1871 demolition and now serves as the entrance of the Nambu Kaikan hall. When it collapsed under snow in 1978 and was repaired, a small Bishamonten statue was found inside it.