To provide a continuously variable transmission which is dimensionally small in the axial direction, compact, of simple construction, and capable of automatically performing ON-OFF of hydraulic transmission in response to the change in the number of revolutions of an input shaft.

A first plunger 14 group of a radial type first hydraulic pump P1, and A second plunger 24 group of a radial type second hydraulic pump P2 connected to the first hydraulic pump P1 through a hydraulic closed circuit, are arranged on a common cylinder body 12 firmly locked to an input shaft 1, and the first pump ring 15 for operating the first plunger 14 group is journalled to a transmission case 5 so as to make the eccentric direction and the amount of eccentricity of the first pump ring 15 variable in relation to the cylinder body 12. Further, a radial crank valve hole which extends over a low-pressure oil path 28 and a high-pressure oil path 29 of the hydraulic closed circuit, is provided in the cylinder body 12, and a clutch valve for closing between both the oil passages 28, 29 by centrifugal action, is loaded in the crank valve hole.