A fixed sheave mounted to an input shaft (22) and a movable sheave mounted to a circular tube member (36) supported so as to be axially slidable relative to the input shaft (22) are constructed from annular members (32) having the same shape. This enables the fixed sheave and the movable sheave to have commonality with each other and makes the shapes of constituent parts relatively simple to facilitate forming of the parts. As a result, productivity is increased.