Ypäjä is a municipality located in the countryside of South-Western Finland.

It belongs to the province of Southern Finland and the region of Tavastia Proper.

The main population centre of Ypäjä is a small village situated on the river Loimijoki, between the towns of Forssa (23 km to the east from Ypäjä) and Loimaa (15 km to the west).

Besides Loimaa, its direct neighbours are Jokioinen, Humppila, Somero and Koski Tl.

Ypäjä is probably best known for horses; the municipality e.g. has an Equine College and hosts an annual international riding competition called Finnderby.