To effectively display the function of a hard mode and a soft mode by enlarging damping force difference between the hard mode and soft mode even in case of the stroke speed of a piston being medium-high speed and allow vafious control modes to be set utilizing the damping force difference.

A retainer 103 constituting a piston valve 100 is composed of a first retaining member 104 protruded vertically to the fixed height from the inner end so as to support an inner end 101a of a plate spring 101 in such a way that the inner end 101a is a fixed end and that an outer end 101b is a free end, and a second retaining member 105 protruded vertically slightly less than the first retaining member 104 so as to become a secondary fulcrum when the plate spring 101 is bendingly deformed.