Binnenmaas () was a municipality in the western Netherlands, in the province of South Holland. The municipality had a population of in , and covers an area of of which is water. It is named after the lake of the same name.
The municipality was formed on 1ÃÂ January 1984 by the merger of the municipalities Puttershoek, Maasdam, Mijnsheerenland, Westmaas, and Heinenoord. On 1 January 2007 the municipality 's-Gravendeel was added to Binnenmaas. On 1 January 2019 it was merged with Cromstrijen, Korendijk, Oud-Beijerland, and Strijen to form the municipality of Hoeksche Waard.
The municipality of Binnenmaas consists of the following communities: Blaaksedijk, De Wacht, Goidschalxoord, 's-Gravendeel, Greup, Heinenoord, Kuipersveer, Maasdam, Maasdijk, Mijnsheerenland, Puttershoek, Reedijk, Schenkeldijk, Sint Anthoniepolder, Westdijk, Westmaas and Zwanegat.
Dutch Topographic map of the municipality of Binnenmaas, June 2015.