A sub-frame of a motorcycle is attached to the rear end of a main frame of the motorcycle and extends rearward. An AMT (Automated Manual Transmission) mechanism is attached to the sub-frame which prevents direct conduction of heat and vibrations generated by an engine on the main frame to the AMT. The AMT mechanism includes a hydraulic clutch actuator, a hydraulic shift actuator, an accumulator, a valve block, a pump, and an oil tank.