To provide a rear wheel braking device for a motorcycle that can reduce an unsprung mass and the number of pieces of components on the rear wheel side of a shaft drive type motorcycle. In a rear wheel braking device for a motorcycle transmitting a drive force of a power unit of a motorcycle to a rear wheel through a drive shaft that extends in a vehicle longitudinal direction, the drive shaft includes a propeller shaft that is connected to a rear end of an output shaft through a universal joint, the output shaft protruding to the vehicle body rear side from a case member of the power unit. A brake disk is attached to the output shaft, the brake disk being braked by a rear wheel brake caliper. The rear wheel brake caliper is fixed to a bracket that is arranged in the case member, and is disposed on the vehicle body upper side of the brake disk.