Ermionida () is a municipality in the Argolis regional unit of the Peloponnese in Greece. The seat of the municipality is the town Kranidi. The municipality has an area of 421 km<sup>2</sup>.
The municipality Ermionida was formed at the 2011 local government reform by the merger of the following 2 former municipalities, that became municipal units:
The province of Ermionida () was one of the three provinces of Argolis Prefecture. It was abolished in 2006. Its territory covered the territory of the present Ermionida municipality.