PURPOSE: To simplify the brake operation during the traveling in a city by generating a brake hydraulic pressure by closing a throttle valve even by the operation of a throttle grip and operating a master cylinder and the driving a brake device.

CONSTITUTION: When a throttle grip 5 is revolved in the opposite direction to the direction of arrow A, the opening degree of a throttle valve is reduced, and the valve is closed to an idling position finally, and the edge surface of an auxiliary rod 14 contacts the inclined surface 53 of a cam. When the throttle grip 5 is revolved in the opposite direction to the direction of arrow A furthermore, the edge surface of an auxiliary rod 14 rides over the inclined surface 53 of the cam, and then the auxiliary rod 14 is shifted leftward according to the revolution quantity of the throttle grip 5. Then, the pivotal installation point of the auxiliary rod 14 and an auxiliary lever 10 forms a force point by the force applied by the cam action, and the auxiliary lever 10 is turned in the clockwise direction around a fulcrum P, and a piston 43 slide in a cylinder 4, and generates a brake hydraulic pressure.