An actuator includes an electric motor, an output shaft and a speed reducer. The speed reducer is configured to transmit rotation, which is outputted from the motor, to the output shaft after reducing a speed of the rotation outputted from the motor. The speed reducer includes an output gear joined to the output shaft and a compound gear. The compound gear includes a large diameter gear, which has a plurality of large gear teeth, and a small diameter gear, which has a plurality of small gear teeth. One of the large diameter gear and the small diameter gear is a metal gear, which is made of a metal member, while another one of the large diameter gear and the small diameter gear is a resin gear, which is made of a resin member, and the resin gear is integrally molded together with the metal gear in one piece.