A friction roller type reduction gear includes a first sun roller so mounted on an input shaft movably in the axial direction of the input shaft, a plurality of first cam grooves formed in the end face of the first sun roller, a cam plate so mounted on the input shaft as is opposed to the first cam groove side of the first sun roller, a plurality of second cam grooves so formed in the cam plate as are opposed to the first cam grooves, rolling elements interposed between the first and second cam grooves, and a cage for holding the rolling elements rollably, while a pitch circle diameter of the position for holding the rolling elements is different from pitch circle diameter of the first and second cam grooves.