An automatic transmission that includes two clutches that are disposed at positions that overlap in an axial direction and are different in a radial direction. The two clutches each include: a clutch drum, a piston that structures a working oil chamber with a portion of the clutch drum used as a cylinder, a plurality of friction plates that engage the clutch drum, and a cancel oil chamber that is disposed on a back surface side of the piston and that cancels a centrifugal hydraulic pressure that acts on the working oil chamber. An inner spline is formed on the clutch drum of one clutch, among the two clutches, that is positioned on an outer diameter side. An outer spline is formed on the clutch drum of the other clutch, among the two clutches, that is positioned on an inner diameter side.