To provide a reciprocating pump having a gas exhaust mechanism capable of suitably and automatically exhausting gas without troublesome work.

The subject reciprocating pump has diaphragm drive chambers and a driving force supply portion 40, and the driving force of the driving force supply portion 40 is transmitted to diaphragms 1A, 1B in the diaphragm drive chambers through operating oil. In the reciprocating pump, operating oil restriction chambers 5A, 5B are disposed between the driving force supply portion 40 and the diaphragm drive chambers, a first gas exhaust portion disposed at upper positions in the operating oil restriction chambers 5A, 5B and second gas exhaust portions disposed at upper positions in the diaphragm drive chambers are provided, each of gas exhaust mechanisms 20A, 20B is constituted by connecting the first gas exhaust portion to the second gas exhaust portion, and back-flow prevention members preventing the back-flow of fluid from the first gas exhaust portions to the second gas exhaust portions are disposed to the gas exhaust mechanisms 20A, 20B.