An automatic transmission that includes two clutches that are provided in mutually different positions in a radial direction while overlapping each other in an axial direction. The two clutches each include a clutch drum; a piston that structures a operating oil chamber while using a part of the clutch drum as a cylinder; a plurality of friction plates that engage the clutch drum; and a cancel oil chamber that is disposed on a back face side of the piston and that cancels a centrifugal hydraulic pressure acting on the operating oil chamber.