PURPOSE: To enable the continuous packing of a long core material with a packing film by extruding a packing film simultaneously with inserting a long core material through an insertion hole at the center of a die formed in the center of an extrusion nozzle delivering it lengthwise.

CONSTITUTION: A delivery means 3 transfers a long core material 4 with feed rollers 7 and 7 at a constant speed and at the centering state. A resin bank 8 is formed in a die 2 in a ring and this 8 allows the extrusion pressure of a melted resin material to be equal in the entire periphery to ensure an equal thickness of a packing film 1. The long core material 4 is inserted through an insertion hole 5 at the center of a die 2 and packed continuously with a packing film being extruded in a tube from an extrusion nozzle 6.