An electromagnetic relay assembly includes an actuator unit and at least one switch unit detachably connected with the actuator unit. The actuator unit includes an actuator casing accommodating therein an electromagnet ic assembly and a movable actuator frame magnetically attracted by the electromagnetic assembly to move between first and second positions,. The switch unit includes a switch casing accommodating therein a switch assembly capable of selectively assuming one of an ON state in response to movement of the movable actuator frame from the first position to the second position and an OFF position in response to movement of the movable actuator frame from the second position to the first position. The actuator casing and the switch casing have mating engagement members by which the actuator unit and the switch unit can be separably connected together while the movable actuator frame in the actuator unit can be drivingly coupled with the switch assembly in the switch unit.
