An electromagnetic switch has a magnetic core having a base member and a disc member. The disc member is made of plates laminated along a pulling direction and has an inner hole. The base member has both a first portion and a second portion having a groove on its outer surface and disposed in the hole. An inner portion of a particular plate among the plates is disposed in the groove so as to fasten the particular plate to the base member. When the core is magnetized in response to excitation of a coil, a plunger is moved toward the first portion of the core along the pulling direction, a movable contact moved with the plunger comes in contact with a fixed contact electrically connected with a motor, and electric power is supplied to the motor through the fixed and movable contacts.