A planetary gear set includes a sun gear; pinions that are positioned around the sun gear and that mesh with the sun gear; and a ring gear that is positioned on the outer side of the pinions and that meshes with the pinions. Each pinion has a plurality of teeth on the outer surface thereof. Each tooth has a first tooth surface and a second tooth surface on opposite sides of the tooth, which can contact tooth surfaces of the sun gear and the ring gear. The deviation of the first tooth surface from the corresponding reference surface differs from the deviation of the second tooth surface from the corresponding reference surface.