In a planet roller speed changer, a plurality of shaft portions of a carrier is disposed such that, when the carrier is displaced in a direction that intersects with the axial direction of an output shaft, the outer periphery of at least one of the shaft portions that are displaced with a displacement of the carrier contacts the stationary ring-side portion of the inner periphery of a corresponding planet roller without contacting the input shaft-side portion of the inner periphery of the corresponding planet roller.