To prevent an engine from being thermally affected by the air that has passed a radiator. A engine and a radiator for cooling the engine are attached to the body frame. An air guide plate permits lead air striking the radiator to a desired position to be disposed between the radiator and the engine. The air guide plate is formed with an upper wall at its upper portion, with lateral walls at its respective left and right lateral portion, and with an opening portion at its lower portion for discharging the discharge air of the radiator.