An automatic transmission comprises a multi-plate brake 70 to brake a specified rotational element of a transmission mechanism, which includes a plurality of frictional plates 71, 71b, a piston 72, a piston cylinder member 73 comprising cylinder in which the piston slides, and oil-pressure chambers 75a, 75b which are formed between the piston and the cylinder and bias the piston 72 toward the frictional plates with an oil pressure supplied thereto, and a valve body 200 to supply the oil pressure to the oil-pressure chambers 75a, 75b. Herein, the valve body 200 is provided in the vicinity of an outer periphery of the piston cylinder member 73 so as to be connected to the piston cylinder member via a connection portion, and there is provided an oil passage to supply the oil pressure from the valve body 200 to the oil-pressure chambers 75a, 75b via the connection portion.