PURPOSE: To carry out the cutting of a moulding material on vibration marks generated in the moulding material at constant pitches so that the exterior appearance of a moulding formed by the cutting may be made satisfactory, by setting the length of the moulding material from the outlet of an extrusion mould to a cutting edge, to a distance which is an integer times as large as the cut length of the moulding.

CONSTITUTION: A moulding material M1 is cooled down in a cooling tank 2, and is cut in a predetermined length (1) by a cutter 4 after being extracted by an extractor 3, so that a moulding body M is obtained. The setting of the cut length (1) of the moudling body M is made by adjusting the distance from a cutting edge 41 to a imit switch LS1. With this arrangement, a slide base 43 is made movable along a rail 44 so that the distance L between the outlet of an extrusion mould 1 and the cutting edge 41 may be adjusted. Further, the distance L is set to a value which is an integer times as large as the cut length (1), upon cutting. Thereby, the cutting may be made on marks which are formed in the moulding material M1 at constant pitches due to vibration generated upon cutting.