Abstract: A multiple reciprocating pump such as a triple diaphragm or piston pump has a drive shaft (28), a plurality of reciprocating rods (48a, 48b, 48c) arranged in parallel with one another at one side of the drive shaft (28) and capable of reciprocating in accordance with rotation of the drive shaft (28); Displaceable members (56a, 56b, 56c) such as diaphragms or pistons secured to the ends of the reciprocating members (48a, 48b, 48c) and defining wall members of pump chambers (54a, 54b, 54c). The wall members (56a, 56b, 56c) are displaceable in accordance with the reciprocating movement of the reciprocating members (48a, 48b, 48c) so as to vary the volumes of the pump chambers (54a, 54b, 54c) thereby sucking in and discharging a liquid. The reciprocating members (48a, 48b; 48b, 48c) which are adjacent to each other in the direction of axis of the drive shaft (28) have different lengths.