Abstract: A fluid compressing apparatus including a cylinder block having a cylinder bore with a diameter penetrating through the cylinder block in a lengthwise direction, a discharge chamber having a diameter larger than the diameter of the cylinder bore, and at least one fluid suction port penetrating into the cylinder block including an interconnected space comprising a fluid discharge port. A piston serves to open and close the suction port while linearly reciprocating within the cylinder bore eliminating need for a separate suction valve assembly. A valve plate separates from and opens the discharge port as a result of the high pressure of the fluid in the cylinder bore, thus compressing the fluid until completely discharged; such that the clearance volume in the cylinder bore is minimized improving compression efficiency.