Electromagnetic actuator

A sealing member which seals a sealed space where a movable core of an electromagnetic actuator is arranged, includes: an inner ring portion and an outer ring portion which are respectively arranged inside and outside in the radial direction, come into contact with the upper surface of a flange of a fixed core and the lower surface of a coil assembly, and are compressed therebetween; and a thin connection portion integrally connecting the inner and outer ring portions. Therefore, the inner and outer ring portions are compressed and escape toward the upper and lower surfaces of the thin connection portion, whereby the axial thickness of the sealing member can be reduced in an assembled state while securing the sealability of the sealing member. As a result, even if the number of windings of the conducting wire is equal to the conventional device, the diameter of the coil and the entire length of the conducting wire are reduced, whereby the resistance and the inductance of the coil are reduced to improve magnetic response.