In an electromagnetic actuator, an electromagnetic drive section forms a flux path between a plunger and an inner yoke, each member being made of magnetic material, and which drives the plunger in an axial direction through electromagnetic force, an operation section has a dog movable between a connection position where it is connected with a mating part and a release position where it is apart from the mating part in the axial direction, and which restrains movement of the mating part in a circumferential direction when the dog is at the connection position, and a retaining ring is interposed between the plunger and the dog such that relative movement of the dog to the plunger in the circumferential direction is permitted and relative movement of the dog to the plunger in the axial direction is restricted.