Onjuku Dam is an earthfill dam located in Chiba Prefecture in Japan.

The catchment area of the dam is 0.6 km2.

The dam impounds about 12 ha of land when full and can store 610 thousand cubic meters of water.

The construction of the dam was started on 1970 and completed in 1977.

This article about a dam or floodgate in Kantō region of Honshu, Japan is a stub.