PURPOSE: To obtain homogeneous extrusion moldings easily by a method wherein a plurality of filters comprising a porous plate and a metal net supported by the porous plate are arranged in the molten resin passage at the tip part of an extruder so that the metal net surfaces can be parallel to each other.

CONSTITUTION: A plurality of filtrating devices 3, 5 comprising a porous plate and a metal net of stainless steel or the like supported by the porous plate are arranged in the molten resin passage 4 at the tip part of an extruder of thermoplastic synthetic resin so that the metal net surfaces of eadh filtrating device are parallel to each other. The ratio l/d of the distance l between a plurality of filtrating devices 3,5 to the inner diameter d of the resin passage is designed to exceed 1, preferably, to take about 2W10. The thermoplastic synthetic resin from a hopper 9 is kneaded by a screw 2, filtrated by the filtrating devices 3, 5 and then extruded from a die 6, cooled in a cooling tank 7 and cut with a cutter 8 to obtain homogeneous pellets.