A continuously variable transmission provided with a rotary shaft characterized in that a ball spline is formed between an inner peripheral surface of a first disc and an outer peripheral surface of an intermediate portion of a rotary shaft, a restraining members for limiting displacement of balls of a ball spline is provided on an inner side of the inner peripheral surface of the first disc, a small-diametered portion is formed on the outer peripheral surface of the intermediate portion of the rotary shaft and between the first disc and a second disc, and the restraining members is mountable through the small-diametered portion with the restraining members and the small-diametered portion axially aligned with each other.