To simplify and make compact a structure of an electromagnetic pump being provided with a pump chamber for varying a volume by an action of a plunger in a frame and feeding a fluid, particularly a gas.

An electromagnetic pump is provided with a solenoid 2; a plunger 3; and a pump chamber 10 for carrying out a pumping action by varying a volume by a bellows member 11 connected to the plunger 3. A projection 3a projecting to the pump chamber 10 is provided on the plunger 3 and a fluid passage 6 axially penetrating through the plunger while including the projection 3a is provided. The bellows member 11 is sealingly fixed to an inner mounting portion 11 while surrounding the fluid passage 6 of the projection 3a of the plunger 3. A one-way valve 12 is provided on an edge surface of the projection 3a and the pump chamber 10 is separated from a sliding surface of the plunger 3 to prevent leakage of the fluid.