Shōjujidate Castle, Medieval castle site in Nanbu, Aomori Prefecture, Japan

Shōjujidate Castle is a medieval hilltop fort in Nanbu, Aomori Prefecture, also called Moto-Sannohe Castle. Its roughly trapezoidal plateau is cut off to the north by a 20-metre-wide dry moat and ringed elsewhere by cliffs over 20 metres high. Excavations found four post-built buildings and 38 pit dwellings; farmhouses and orchards now occupy parts of the site.

Shōjujidate Castle was built by Nanbu Mitsuyuki, who accompanied Minamoto no Yoritomo in the 1189 conquest of the Hiraizumi Fujiwara and received estates in Nukanobu District. The Sannohe Nanbu clan used it as their residence for about 200 years, from the 11th chieftain Nobunaga to the 24th, Harumasa. In June 1539 a retainer, Akanuma Bitchū, set it on fire; Harumasa later moved to Sannohe Castle, and the site became known as Moto-Sannohe Castle.

The castle's name comes from Shōjo-ji, the Nanbu clan's family temple beside the ruins. Sankō-ji, a Rinzai Zen temple just north of the former Shōjo-ji, holds the graves of the 26th chieftain Nanbu Nobunao and his wife, plus the mortuary chapel of the 27th chieftain Nanbu Toshinao. Moto-Sannohe Hachiman-gu, south of the main site, keeps the grave of the 23rd chieftain Nanbu Yasunobu.

The ruins lie on a hilltop southwest of the Shōjuji settlement, cut off to the north and east by a dry moat about 20 metres wide and hemmed in on the west and south by slopes over 20 metres high. Parts of the site are private land with farmhouses and orchards, so stay on the paths. The grounds are 700 metres west of Hiragasaki Castle and 4 kilometres north of Sannohe Castle.

The castle site is not a single plot: the national historic site designation of 2004 covers three areas — the castle itself, the Sankō-ji temple district with the Nanbu family graves, and the Moto-Sannohe Hachiman-gu shrine district. Excavations found four post-hole buildings and 38 pit dwellings, and much of the medieval ground plan survived because the site was never heavily redeveloped.