To provide a planetary gear wherein noises made by resonance of pinion shafts are reduced by so constituting the gear that resonance frequencies of the plurality of pinion shafts are made different from each other.

The planetary gear 8a includes a plurality of pinion gears 31, and a plurality of pinion shafts 45a, 45b, 45c supporting the pinion gears 31 respectively. The pinion shafts 45a, 45b, 45c have axially extended holes 46a, 46b, 46c in the insides respectively. Out of the plurality of the pinion shafts 45a, 45b, 45c, the shape of the axial hole of at least a pinion shaft is different from the shapes of the axial holes of the other pinion shafts 45a, 45b, 45c.