PURPOSE: To enable the continuous discharge of a food material at a constant rate without causing pulsation, by providing an outer circumferential chamber having definite volume and encircled with a flat plate, a circumscribed cam, the outer face of a hollow cylinder and a side wall of a housing and making the material to be transferable under a definite pressure at a constant volume.

CONSTITUTION: A freely insertible flat plate 5 is inserted into a slit 4 formed on a generator of a hollow cylinder 2 in axial direction and both ends of the flat plate 5 are made to contact with a circumscribing cam 8 and an inscribing cam 9, respectively. The apparatus in provided with an outer circumferential chamber 11 encircled with the flat plate 5, the circumscribing cam 8, the outer face of the hollow cylinder 2 and a side wall of a housing and an inner circumferential chamber 12 encircled with the flat plate 5, the inscribing cam 9, the inner face of the hollow cylinder 2 and a side wall of the housing. The outer chamber 11 is made to be connected with the inner chamber 12 at the back of the flat plate 5. A relative decrease in the volume of the outer circumferential chamber 11 and a relative increase in the volume of the inner circumferential chamber 12 take place in the zone 15 by the rotation of the hollow cylinder 2. The zone 15 is connected with a zone 16 where the outer circumferential chamber 11 has a definite volume. At least two flat plates 5 are present in the zone 16.