To restrain the chattering of a contact and improve a contact life, by reducing the attracting speed of a plunger in a place where the air gap of an electromagnetic switch is small.

A plunger 39, housed in an electromagnetic switch 5, is faced to a grand plate 37 via an air gap G in the inner periphery of an attracting coil 38, and receives magnetic force to be attracted to the grand plate 37 side when the coil 38 is electrified to flow magnetic flux in a magnetic circuit. A hollow part 39a is provided in the lower end part on the opposite side to the air gap G side; and in the hollow part 39a, a hole having prescribed depth is provided toward the inside from the bottom surface of the plunger 39, and then a lid body 39b is provided on the opening part of the hole to form a sealed hollow space.