The infusion pump has a rigid housing (10) in which a flexible sheath (15) in the form of a bellows is arranged. A plate-shaped advance part (14) which is under the action of a frustoconical helical spring (20) presses against the sheath (15). The injectable solution contained in the sheath (15) is fed to an outlet line (25) via a flow-restriction point (24). The shape and pre-tension of the spring (20) result in a virtually constant spring force and thus uniform infusion pressure over the entire emptying distance (h). <IMAGE>
