A synchronizer for a transmission includes a shift rail, a first sleeve, a second sleeve, and a stopper. The shift rail includes a first shift fork and a second shift fork that are provided integrally with each other. The first sleeve is movable in a first direction along an axial direction from a predetermined first standby position to synchronize a first gear with a rotating shaft. The second sleeve is movable in a second direction along the axial direction from a predetermined second standby position to synchronize a second gear with the rotating shaft. A distance between the second sleeve at the predetermined second standby position and the stopper in the axial direction is smaller than a distance between the first sleeve at the predetermined first standby position and the third gear in the axial direction.