To provide an emergency stopping device capable of preventing colli sion due to sudden forward travel or sudden reverse travel of a vehicle by stepping on an accelerator pedal by mistake with intention of stepping on a brake pedal in a temporary stop, start or the like.

An accelerator mechanism 1 is provided with a hydraulic control device 6 allowing an appropriate movement of a piston 14 by hydraulic fluid 21 in a cylinder 12 to provide an appropriate speed control by an accelerator lever 4 operation when the accelerator pedal 5 is stepped on with applying force in a normal speed condition, and giving resistant force to the movement of the piston by hydraulic fluid 22 in the cylinder 12 to obstruct stepping-on operation of the accelerator lever 4 when the accelerator pedal 5 is stepped on with applying force in an abnormal speed condition.