PURPOSE: To cause particles of metal or catalyst to be accumulated and deposited uniformly over the filtering surface of carbon paper by laying a sheet of carbon paper on a perforated plate of a filter comprising a perforated plate to effect suction filtering therethrough.

CONSTITUTION: By filtering solutions containing deposits and/or powders by means of a filter comprising a perforated plate, deposits and/or powders are caused to be deposited over a sheet of a carbon paper in such a way that a sheet of carbon paper is laid on a perforated plate of a filter having a perforated plate to effect suction filtering through said sheet of carbon paper, wherein the thickness of the carbon paper is 0.3-0.8mm. As a result, particles of metal or catalyst are deposited uniformly over the carbon paper.