Monnyu Dam (Japanese: 門入ダム) is a gravity dam located in Kagawa Prefecture in Japan.

The dam is used for flood control and water supply.

The dam impounds about 21 ha of land when full and can store 2900 thousand cubic meters of water.

The construction of the dam was started on 1980 and completed in 1998.

This article about a dam or floodgate on Shikoku, Japan is a stub.