To reduce a so-called nose dive phenomenon, in which a vehicle body B leans forward when braking, even when a storage amount of a tank T decreases.

A working machine for being travelled includes a hydrostatic transmission with a closed circuit formed of a variable displacement pump P and a hydraulic motor M connected through a pair of connection flow paths 2, 3. In the working machine, a short-circuit passage 4 is provided in the closed circuit and a shut-off valve 5 is provided in the short-circuit passage 4 for opening and closing the short-circuit passage 4. When the shut-off valve 5 is kept at an open position, if a brake is operated while the tank T is empty, the hydraulic motor M gradually stops while performing pumping operation.