An actuator maintains high efficiency, can react to an increase in pole, has a high part fit, and can be manufactured at low cost while it is thinned. The actuator includes a magnet 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 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 whose surface perpendicular to the rotational axis is bonded to the magnet, and is made of a soft magnetic material; and a coil, which is located on substantially the same surface as that of the magnet, is fixed to the stator, and excites the stator and the disk portion.