The present invention concerns a device (1) for portioning a food product (3) continuously extruded from a filling apparatus, preferably for making meat-base elongated extrusions in form of sausages, frankfurters and the like, wherein two front and opposed pincers (4) carry out a succession of neckings onto the extrusion (3), via outwardly and inwardly reciprocating alternate motions therebetween parallel, carried out by plural gearings, the kinematic motion enabling the pincers (4) to carry out axial displacement s concomitantly to said reciprocating motions, so as to follow the extruded product (3) in the feeding direction thereof and in predetermined lenghts which are variable by variably adjusting the angular velocities of said gearings.