A friction engagement element (CLx) is provided radially outside of a peripheral wall portion (32) of a clutch drum (30) and configured to be engaged by a piston (40). A piston (70) is provided radially inside of the peripheral wall portion (32) and configured to engage and a friction engagement element (CLz). A first peripheral wall portion (321) of the peripheral wall portion (32) includes through-holes (321a) communicating a radially inside of the first peripheral wall portion (321) with a radially outside thereof. A through-hole (87) is provided radially inside of the piston (70). The piston (70) includes a communication passage (79) radially passing through the piston (70) and communicating the through-hole (87) with the through-holes (321a) such that lubricating oil is supplied through the communication passage (79) and the through-holes (321a) to the radially outside of the clutch drum (30) when the piston (70) is in an initial position.