To provide a motor with a reduction gear capable of reducing overhanging to the outer periphery side of the motor, and the axial thickness of a rotary shaft.

This motor 30 with the reduction gear is installed so as to output torque inputted from an outer-rotor type motor 32 from an output shaft 38 through the reduction gear 34. The reduction gear 34 is an epicyclic gear device 30 comprising a sun gear 54 connected to the output shaft 38, one or more epicyclic gears 40 coupled with the output shaft 38 and rotating on its axis while moving around the outer or inner periphery of the sun gear 54, an annular fixed gear 56 which is an inner-teeth gear engaged with the respective epicyclic gears 40 and surrounding the orbital periphery of the respective epicyclic gears 40 and stops relatively to the respective epicyclic gears 40, and a carrier 42 fitted with the epicyclic gears 40. The carrier 42 is a rotor yoke 42 of the motor 32, and each of the epicyclic gears 40 is disposed so as to face a stator 46 in the motor 32 with the rotor yoke 42 sandwiched.