An objective is to provide a reciprocating pump kept from lowering its performances, while restraining the cost from increasing.Collars 14, 20, 21 made of a material more excellent in resistance to corrosion than a manifold 3 are interposed between the manifold 3 and sealing members 10, 22, 23 for liquid-tightly sealing the manifold 3, so as to prevent the parts in contact with the sealing members 10, 22, 23 from being corroded by a liquid for use, and fully exhibit sealing functions, thereby preventing leakage from occurring in a pump chamber 4 and the pressure oscillation from being increased by the leakage, while the collars 14, 20, 21 made of the material excellent in resistance to leakage are used only in the parts in contact with the sealing members 10, 22, 23.