To stop a rotor of an electromagnetic actuator by its own damping torque.

An electromagnetic actuator includes: a rotor 50 which has a magnetized rotor part and a driving pin and is turned around a prescribed center axial line S; an excitation coil 80; and a yoke 60 including a first magnetic pole part and a second magnetic pole part which define an arcuate surface facing an outer peripheral surface of the magnetized rotor part and edge parts formed at ends of the arcuate surface and generate mutually different magnetic poles due to power supply to the coil. The magnetized rotor part comprises a first magnet 52 having an outer peripheral surface divided into two and magnetized with S and N poles with a first magnetization boundary surface 52a as the boundary, and a second magnet 53 which is laminated on the first magnet in a direction of the center axial line and has an outer peripheral surface divided into two and magnetized with N and S poles with a second magnetization boundary surface 53a shifted from the first magnetization boundary surface by a prescribed twist angle α around the center axial line, as the boundary. Thus the rotor is stopped by its damping toque and is held in both end positions of an operation angle.