To provide an actuator and a robot which can operate smoothly without generating any backlash.

The actuator comprises an output gear 34 provided on one rotating output shaft 30 coaxially with the center of rotation thereof, a first motor 22 and a second motor 23 generating a torque, respectively, first and second decelerating means for increasing torques generated from the first motor 22 and second motor 23 by deceleration them through a first gear train 36 and a second gear train 37 provided between the output gear 34 and the first motor 22 and then transmitting the increased torque to the output gear 34, and a control means 81 for controlling the first motor 22 and second motor 23 to generate torques in reverse direction in order to control driving thereof and rotating the output gear 34 based on the difference of torques generated from the first motor 22 and second motor 23.