To improve a friction ring control device so that a transmission is formed as small as possible and usable as a vehicular transmission.

A conical friction ring type transmission is provided with two rotating conical friction wheels 3, 4 provided reversely on two parallel axes 1, 2 and having the same conical angle, and a friction ring 5 coming in contact with both conical friction wheels 3, 4 and surrounding one conical friction wheel 3. This friction ring 5 is guided along the bus-line of both conical friction wheels 3, 4. The friction ring 5 is held in a retainer 6, and the retainer 6 is guided along the bus-line of both conical friction wheels 3, 4. The retainer 6 is pivotally fixed to a rotary shaft 14 and arranged in such a way as to be able to oscillate around the rotary shaft 14 by a driving device.