A roller screw is provided having a structure suitable for circulating rollers. The roller screw has a screw shaft 5 with a spiral roller rolling groove 5a formed on an outer peripheral surface thereof; a nut 6 with a spiral roller rolling groove 6a opposed to the roller rolling groove of the screw shaft and formed on an inner peripheral surface thereof; and a plurality of rollers 7 arranged in a load roller rolling path 9 between the roller rolling groove 5a of the screw shaft 5 and the roller rolling groove 6a of the nut 6. Inside the nut 6 is provided a roller return path 11 extending linearly in parallel with an axis line of the nut 6. To opposite end faces in an axis line direction of the nut 6 are attached direction change path forming members 13 in which direction change paths 10 to connect the load roller rolling path 9 and the roller return path 11 are formed. The roller return path 11 is twisted to rotate an attitude of each of the rollers 7 while the rollers 7 move in the roller return path 11.