A planet roller speed changer comprising: an input shaft; a stationary ring disposed around the input shaft so as to be concentric with the input shaft; a plurality of cylindrical planet rollers that are in rolling contact with both the input shaft and the stationary ring; an output shaft; and a carrier having a plurality of shaft portions each of which is disposed in a corresponding one of the planet rollers, passes through the corresponding one of the planet rollers, and supports the corresponding one of the planet rollers in a loosely fitted state such that the corresponding one of the rollers is rotatable, the carrier being fixed to the output shaft so as to be rotatable together with the output shaft, characterized in that the shaft portions of the carrier are disposed such that, when the carrier is displaced in a direction that intersects with an axial direction of the output shaft, an 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 an inner periphery of the corresponding planet roller without contacting the input shaft-side portion of the inner periphery of the corresponding planet roller, and when the center of rotation of the carrier is aligned with the center of revolutions of the planet rollers, the position of the outer periphery of each shaft portion is set such that, in the case where the center of each shaft portion, the center of the corresponding planet roller and the center of the input shaft are aligned on a single straight line, a clearance (CL 2) is formed between the shaft portion and the planet roller on the stationary ring side, and a clearance (CL 1) between the shaft portion and the planet roller on the input shaft side is larger than the clearance (CL 2) between the shaft portion and the planet roller on the stationary ring side. an input shaft; a stationary ring disposed around the input shaft so as to be concentric with the input shaft; a plurality of cylindrical planet rollers that are in rolling contact with both the input shaft and the stationary ring; an output shaft; and a carrier having a plurality of shaft portions each of which is disposed in a corresponding one of the planet rollers, passes through the corresponding one of the planet rollers, and supports the corresponding one of the planet rollers in a loosely fitted state such that the corresponding one of the rollers is rotatable, the carrier being fixed to the output shaft so as to be rotatable together with the output shaft, characterized in that the shaft portions of the carrier are disposed such that, when the carrier is displaced in a direction that intersects with an axial direction of the output shaft, an 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 an inner periphery of the corresponding planet roller without contacting the input shaft-side portion of the inner periphery of the corresponding planet roller, and when the center of rotation of the carrier is aligned with the center of revolutions of the planet rollers, the position of the outer periphery of each shaft portion is set such that, in the case where the center of each shaft portion, the center of the corresponding planet roller and the center of the input shaft are aligned on a single straight line, a clearance (CL 2) is formed between the shaft portion and the planet roller on the stationary ring side, and a clearance (CL 1) between the shaft portion and the planet roller on the input shaft side is larger than the clearance (CL 2) between the shaft portion and the planet roller on the stationary ring side.