The invention provides a filter for an extruder. The filter achieves functions of protecting a filter main body (1), ensuring the intensity of a perforated plate (2), reducing pressure loss in a filtering process and preventing cleaning deterioration and weight increase. The filter for an extruder comprises a filter main body (1), a perforated plate (2) supporting the filter main body (1) from the downstream side and comprising a plurality of through holes (23) forming paths of a high molecular material and a support body (3) supporting the perforated plate (2) from the downstream side. The support body (3) is composed of a frame section (31) which can be pressed against the outer diameter part of the perforated plate (2) and a plurality of beam parts (32) extending the inner circumferential side from the frame section (31).