A rear portion structure (100) of a motorcycle (1) comprises a chassis frame (5); a rear wheel (17) positioned below the rear portion of the chassis frame (5); a fender main body portion (110) anchored to the rear portion of the chassis frame (5) and positioned above the rear wheel (17); a fender hanging portion (120) configured separately from the fender main body portion (110) and covering at least a portion of the rear wheel (17); and a support stay (130) anchored to the rear end portion of the chassis frame (5) (rear end frame portion (5a), extending aft approximately horizontally from the rear end portion, and supporting the fender hanging portion (120).