PURPOSE: To remarkably reduce shock in a hydraulic cylinder by lowering the hydraulic pressure in an operational oil supply side circuit when the pressure in a tube at the time of a cushioning action becomes higher than a preset pressure.

CONSTITUTION: A bypass valve 10 pressed in contact with the end face 15 of a circular hole 14 by a compression spring 13 is provided on the outside surface at the end of the cushion chamber 8 side of a tube 2. A piston 4 moves near a stroke end, a block 5 goes in a cushion chamber 8 and the hydraulic pressure in a bottom chamber 3 exceeds a preset hydraulic pressure by the compression spring 13 of the bypass valve 10 and then a spool 11 is shifted, the primary side pipes 20, 21 are connected to each other via the circular hole 14. A rod chamber 22 side hydraulic pressure is thereby lowered and the piston 4 abuts the internal end face of the tube at the entrance portion of the cushion chamber 8 at a low speed and under a low pressure. Accordingly, shock is remarkably relieved.