Sekiyado Castle, Japanese castle in Noda, Japan

Sekiyado Castle is a Japanese castle site in Sekiyado, Noda, Chiba Prefecture. The keep standing today is a mock three-storey tower built in 1995 for the Chiba Prefectural Sekiyado Castle Museum, not on the original foundations. It has tiered white plaster walls, dark tiled roofs with upturned eaves, triangular gables and small windows, and rests on a sloping base of large irregular grey stones.

A fortification existed here from the early Muromachi period, built by Yadoya Mitsusuke or Yadoya Shigesuke, and was destroyed in the Hōjō campaign of 1565–1574. Matsudaira Yasumoto, Ieyasu's half-brother, rebuilt it in 1590 and founded Sekiyado Domain. In 1671 the keep was replaced by a three-storey yagura modelled on Edo Castle's Fujimi Yagura. Abandoned in 1872, the castle was pulled down by 1875.

The museum inside displays tools and models explaining how people once controlled flooding and lived with the two large rivers. The exhibition helps visitors understand why this fortress was built at exactly this point where waters converge.

The museum keep stands apart from the castle ruins, which river works and farmland consolidation have largely erased; only part of the honmaru and a dry moat remain. From Kawama Station north exit, an Asahi bus toward Sakai-machi takes about 32 minutes to Shin-machi stop, then 15 minutes on foot. By car it is about 13 minutes from the Ken-o Expressway Sakai-Furukawa interchange.

The keep visible today is a 1995 concrete reconstruction built as an annex to the Chiba Prefectural Sekiyado Castle Museum, not on the original foundations and modelled on generic castle forms rather than this site's own records. The real three-storey yagura stood elsewhere and its ground has been altered by river works.