An annular member is installed on a circular cylinder section of a trunnion, and a roller member, in the inner periphery of which a needle bearing is held, is installed on the circular cylinder section. The needle bearing is held between a flange section formed on one end of the roller member and the annular member installed on the trunnion with a predetermined gap between them. Further, a gap (X) between the needle bearing and the annular member is set to satisfy the following relationship. X>R/2·(1/cos θ max−1) where R: Radius of rotation of the center of the roller member relative to the center axis of an outer member. θ max: Maximum inclination angle of an inner member.