Pump device having means for restricting the movement of a pump member

A pump device comprising a support member (82; 220; 288; 328; 406, 408; 450; 502) having a fitting recess, a movable member (80; 276; 322; 402, 404; 514) which is reciprocated in said fitting recess to suck a working fluid, pressurize the fluid and deliver the pressurized fluid, and a movement restricting device (154; 210; 228; 244; 252; 298; 338; 460; 540) operable to deform a wall (86; 208; 226; 288; 332; 406; 408; 450; 516) at least partially defining the fitting recess of the support member, such that the wall is deformed toward the movable member, for restricting a reciprocating movement of the movable member in the fitting recess, at least when an amount of the pressurized fluid required to be delivered by the pump device is smaller than a nominal delivery amount of the pump device.