PURPOSE: To remove economically and efficiently a foreign matter, by a method wherein styrene foam content in a styrene foam resin waste matter with which the foreign matter is mixed is melted by a solvent and liquefied, a mixed liquid with the foreign matter is filtered by a rotary-beltlike strainer and solid dregs left behind on the surface of a belt is discharged by turning the belt.

CONSTITUTION: A waste matter of styrene foam loaded through a hopper is crushed finely by a rotary crushing cutter and dropped down through meshes of a strainer (a). Operation circulating the foam styrol to a spray nozzle by a pump is repeated until the styrene foam is melted. Since unmelted styrene foam is sent out for pyrolysis, a liquid level of a solvent is lowered down underneath a mesh belt, a solid matter not melted into the solvent is allowed to stick to a filter surface of the mesh belt and a melted liquid is separated from the solid matter. After filtration, the belt is turned and a filter surface to which the solid matter is stuck is exposed out of a liquid level. Then a fresh solvent reclaimed by a pyrolysis furnace is cast into a tank 1 and melting operation is repeated again.