There is provided an electromagnetic contactor which can easily and inexpensively change the DC operation type to the AC operation type. The electromagnetic contactor includes an electromagnet that opens and closes a contact by using DC excitation of a coil, a lower case that accommodates the electromagnet, external coil terminals that are disposed in the lower case beside the electromagnet, and a substrate that is accommodated in the lower case, and that has a rectifier circuit whose input side is connected to the external coil terminals and whose output side is connected to the coil so as to output a DC after converting an input AC to the DC. An inner surface of the lower case has a groove between the electromagnet and the external coil terminals. The substrate is held by being inserted into the groove.