Abstract: A sealing device for a reciprocating pump of the type having a pump housing provided with a bore formed therein. The bore is provided at its one end with an opening through which it communicates with the exterior of the pump housing while the other end of the bore receives a reciprocating member such as a plunger. The sealing device includes a seal case received in the bore and having a bore through which the reciprocating member extends, a sealing member such as a packing held on the inner periphery of the seal case and having an inner peripheral surface adapted to be slidingly contacted by the outer peripheral surface of the reciprocating member, a closure separate from the pump housing and removably attached to the pump housing so as to close the opening on the one end of the bore, and a coiled compression spring loaded between the closure and either one of the seal case and the sealing member.