An automatic transmission equipped with: a plurality of rotary shafts, including an output shaft for outputting driving force; a plurality of gears, including an output-side gear provided on the output shaft; a plurality of synchronization mechanisms, including an output-side synchronization mechanism for coupling the output shaft and the output-side gear; a shift position detection unit for detecting which of a plurality of shift positions, including a neutral position and a neutral position, has been selected; and a control unit for activating a synchronization mechanism other than the output-side synchronization mechanism and coupling a rotary shaft other than the output shaft and a gear other than the output-side gear when the shift position detection unit has detected the neutral position or a parking position.