A motorcycle is provided with a rear fork attached to a body frame so as to swing up and down freely. A rear wheel is attached to the rear end portion of the rear fork, a gear case is attached to a side of the rear wheel, and a drive shaft is provided between the gear case and an output shaft of a power unit. The output of the power unit is transmitted to the rear wheel via the drive shaft and the gear case. In the motorcycle, the gear case is supported by a rear-wheel axle provided in the rear end portion of the rear fork. A torque rod, which links an outer periphery portion of the gear case with the rear fork, serves as a stopper for rotation of the gear case. The resulting configuration provides a shaft-drive system that reduces the assembling time of the torque rod, and improves the productivity of the main line.