To provide an actuator which maintains high efficiency, can react to an increase in pole, has good assemblability, and can be manufactured at a low cost while it is thinned.

The actuator includes: a magnet 1 which is formed in a ring shape, in which at least one surface perpendicular to a central axis thereof is divided in a peripheral direction and alternately plane-magnetized in different poles; a stator 3 including a plurality of magnetic pole teeth opposed to the magnetized surface of the magnet; a rotor which is held to be rotatable about a rotational axis as a center, includes a disk portion 5b whose surface perpendicular to the rotational axis is bonded to the magnet, and made of a soft magnetic material; and a coil 2 which is located on substantially the same surface as that of the magnet, fixed to the stator, and excites the stator and the disk portion.