Abstract: A reverse gear system for a motorcycle includes a shifter for rotatably supporting the idler gear, locating the idler gear in a separation position to disengage the idler gear from the main-shaft-side gear when the shifter is set in a retracted position, and for locating the idler gear in an engagement position to engage the idler gear with the main-shaft-side gear when the shifter is set in a forward position; and a holding unit for provisionally holding the shifter selectively in a state with the shifter being set in the retracted position and in a state with the shifter being set in the forward position. The idler gear is combined with the shifter so that the idler gear has a shaft member formed thereon so as to be rotatably inserted in bearing apertures formed in the shifter. The bearing apertures are formed so as to have a length along a shifting direction of the shifter, the length being larger than a diameter of the shaft member.