An automatic transmission comprises a friction engaging means having a plurality of first plates (23a) splined to a hub (20a) and a plurality of second plates (23b) splined to a drum (20) and disposed in an interleaving relation to the first plates (23a), an one way clutch provided in the hub (20a) and having a plurality of sprags (29) for locking the rotation of the hub (20a) when the hub (20a) rotates in a locking direction and a control means for temporarily releasing the friction engaging means for a specified timespan when the friction engaging means is in an engagement condition and when the hub (20a) rotates in a locking direction. <IMAGE>
