An automatic transmission that includes two adjacent clutches. Two clutches each include a clutch drum, a piston that structures an operating oil chamber with a portion of the clutch drum used as a cylinder, a plurality of friction plates that engage with the clutch drum, a cancel oil chamber that is arranged on a back surface side of the piston and that cancels a centrifugal oil pressure acting on the operating oil chamber, and a return spring that is provided within the cancel oil chamber and that is structured between a cancel plate and a back surface of the piston and that biases the piston toward the operating oil chamber.