A shift-drum speed change mechanism includes a first drum spring biasing a first drum toward a first side in an axial direction, which is a side on which a first slider comes into contact with a first speed change member, a first fork spring biasing a first shift fork toward a second side in the axial direction, which is a side opposite to the first side in the axial direction, with a weaker biasing force than the first drum spring, and a first stopper member for the first drum, defining an end of movement of the first drum toward the first side in the axial direction.