To solve a problem on a conventional known swing valve structure which has a swing valve as a check valve for preventing the flow of liquid in the opposite direction to a water feeding direction or which has a swing valve in a forcible feed port of a pump for forcibly feeding concrete or mortar, in order to improve the performance of the swing valve itself, wherein working conveniences of the swing valve have not been taken into account.

This swing valve structure comprises a void provided in the water suction port of a pump casing, and a swing valve and a valve seat fitted into the void, the swing valve having a peripheral edge fitted into a clearance between the pump casing and the valve seat. Thus, no trouble occurs that the swing valve falls off when caught on a hand during mounting or repairing work.