To obtain shredder dust useful as fuel.

A waste car is crushed, and iron and a non-ferrous metal are recovered from the formed crushed matter to obtain recovered crushed matter and an outside insulating cover is peeled from a conductive wire being the core material of conductive wiring and the conductive wire is recovered to obtain conductive wire recovered dust. The insulating cover is charged to be recovered from the conductive wire recovered dust by electrostatic sorting to treat the waste car as target dust and a fuel oil additive for the electric furnace is manufactured by molding the target dust.