Abstract: A spool type switching valve to be used for the switching operation of a diaphragm pump or a similar device, which simultaneously insures both preventing abrasion of the detent mechanism and obtaining thorough operation of switching the spool. A spool is movably fitted inside a sleeve and is prevented from standing still at a neutral point by a detent mechanism provided at one of its ends. The detent mechanism comprises a spool operator fitted around a shaft section at one end of the spool as one body, a spring holder at the end of the sleeve retains a pair of C-shaped wire springs of a circular cross-section fitted between the spool operator and the spring holder. As the spool passes the neutral point, spring forces snap the spool to the extremity of its range, thereby preventing stopping of the spool in the neutral position. An axial clearance permits the spool operator to begin moving before the spool moves.