A transmission includes a first shaft which is rotatably supported by a first radial bearing, a ring member which is connected to an end portion of the first shaft, a sun roller which is disposed inside the ring member in a radial direction, a second shaft which extends from the sun roller, a plurality of planetary rollers which are disposed in a state of being in contact with an inner peripheral surface of the ring member and an outer peripheral surface of the sun roller, and a planetary roller supporting member which rotatably supports the planetary roller and restrains a movement of the planetary roller in the circumferential direction, in which the ring member is in contact with the plurality of planetary rollers in a state of pressing the plurality of planetary rollers inward in the radial direction so that the plurality of planetary rollers face the sun roller.