To provide an inlet/delivery valve for a reciprocating pump of a water jet weaving machine.

This inlet/delivery valve for the water jet weaving machine includes a tubular body, a valve seat which is jointed to one end of the body, in which an inflow hole for fluid is formed in the center, and which flows the fluid through the body, a support holder which is jointed to the other end of the body and in which a hollow support portion is formed in the center and an outflow long hole from which the fluid flows into the body flows is formed at the edge of the support portion, and an opening/closing valve which has a handle portion inserted into the support potion so as to be freely slid and opens/closes an inflow hole of the valve seat. A handle section of the opening/closing valve includes a jar-shaped curvature portion of which the side surface is protruded outward. The curvature portion is formed out of at least one curvature radius. Therefore, it is possible to minimize various resistances generated at the time of a sliding operation of the opening/closing valve, and reduce variation in the resistance at the beginning of valve operation and during the operation, thus keeping the opening/closing time quick and constant.