PURPOSE: To reduce an exciting current so as to miniaturize an actuator by turning a yoke serving as an outer rotor with respect to an armature serving as a stator, to be positioned at either of two positions.

CONSTITUTION: An armature 1 is constituted of a member of arm portions 1b-1d, which are formed integrally with each other and are fixed to terminal portions of a shaft portion 1a made of a magnetic material. A bobbin 8, where a coil 9 is wound, is insertedly disposed in the middle portion of the shaft portion 1a. A yoke 5 is constituted of a cylindrical portion 5a made of a magnetic material, projections 5b-5e formed at both ends of the cylindrical portion 5a, and a hook 10. A permanent magnet 4 is interposed between the projection portions 5b. When a exciting current is supplied to the coil 9, the cylindrical portion 5a is turned on the outer periphery of a flange portion of the bobbin 8 as a bearing until the projection portions of the yoke 5 abut against the side surface of the arm according to the orientation of the current. Consequently, the armature can be driven at a small exciting current, thereby miniaturizing an actuator.