An automatic transmission includes: a frictional engagement element arranged to be switched from an engagement state to a disengagement state at a switching from a running range to a neutral range, and including: frictional plates; a first piston arranged to push the frictional plates; a second piston arranged to push the frictional plates; a first hydraulic chamber arranged to receive a hydraulic fluid for pushing the first piston; and a second hydraulic chamber arranged to receive a hydraulic fluid for pushing the second piston; a first discharge speed switching section arranged to switch only a discharge speed of the hydraulic fluid of the first hydraulic chamber; and a control unit configured to increase the discharge speed of the hydraulic fluid of the first hydraulic chamber during a predetermined time period by the first discharge speed switching section at the switching from the running range to the neutral range.