To solve the disadvantage in a continuously variable transmission in which a rotation transmitting body is interposed between a pair of disks mounted on a main shaft and a ball spline is set between one disk and the main shaft wherein contact surface pressure increases by point contact in the ball spline and requires excessively precise molding of a spline groove.

A continuously variable transmission has a power roller 4 interposed between the pair of disks 2 and 3 mounted on the main shaft 1, and the ball spline 6 set between the main shaft 1 and the input disk 2, which ball spline includes the spline grooves 15 and 16 formed respectively in the main shaft and the disk, balls 17 engaged with both spline grooves 15 and 16, and rollers 18 for sharing a load when a given load on the main shaft 1 from the input disk 2 deforms the balls 17. When the load is increased to or over a given level, the spline grooves 15 and 16 and the rollers 18 are brought into line contact to reduce contact surface pressure.