A planetary carrier supports a geared rotor from an inside in a radial direction, and receives a radial load in a first region, which is offset to one end from a center position in an axial direction. A ball bearing roller supports the planetary carrier from an outside in the radial direction in a second region, which is offset to an other end from the center position. The ball bearing roller is a single-row ball bearing roller that has an outer ring supported by a drive rotor, an inner ring which supports the planetary carrier, and a plurality of rolling elements which are rotatably installed in a single row to be in contact with and between the outer and the inner rings. The geared rotor is tilted relative to the axial direction, and contacts a driven rotor in the axial direction. An angle of the geared rotor relative to the axial direction is set to be smaller than a maximum allowable angle at which the inner ring is allowed to be tilted relative to the axial direction.