PURPOSE: To simplify a brake device provided with a piston for braking which is operated to a brake side by energizing force of a spring by arranging a switching valve which can discharge hydraulic oil to the piston and an operating pedal which operates the switching valve to hydraulic oil discharging side.

CONSTITUTION: There is provided a switching valve 25 at a connecting point between an oil passage 23 on a hydraulic cylinder 20 side and an oil passage 22 on a pump 11 side. The switching valve 25 is provided with a running position 25a and a braking position 25b. Besides, a brake pedal 27 and the switching valve 25 are interlockingly connected. Unless the brake pedal 27 is depressed, the switching valve 25 stays at the running position 25a. By operating and stopping an engine 1 in this condition and the operation of the switching valve 13, the hydraulic cylinder 20 is operated so that it may extend and contract. When the brake pedal 27 is depressed during operating the engine 1, the switching valve 25 is operated at the braking position 25b, by which hydraulic oil from the pump 11 is removed into a tank 26, so that the hydraulic cylinder 20 extends to make a braking condition.