PURPOSE: To easily obtain electromagnetic iron core in different shapes by mixing iron powder and plastic in the specific rate under normal temperature, plasticizing plastic by kneading it with kneading injection molding machine and by directly injecting the plastic into the die through the injection molding machine.

CONSTITUTION: A raw material inserting hole 3 and an air exhausting hole 13 are provided to a cylinder 2 of which external side is surrounded by a heater 15, a screw 16 which is rotated by driving system 18 and is provided with a groove 12 which is lasted in the axial direction is inserted into the cylinder 2 and an injection nozzle 5 is provided at the end of cylinder 2. On the entrance hole 3, the fixed amount feeders 1A and 1B which supply different kinds of materials are provided. Thus, the iron powder of 91W93% and plastic of 9W7% are accommodated therein. Moreover, the cylinder 2 is divided, from the side of entrance 3, into the feed preheating part I , plasticizing and kneading zone II, air exhausting zone III, measuring zone IV. Of these zones, the zones II and IIIare directioned to the advancing direction and diameter of screw 6 is gradually reduced. Thereby, the raw material pushed out from the nozzle 5 is injected into the metal die.