To efficiently utilize steelmaking slag as the industrial waste together with lead glass and/or boro-silicated glass in waste electric appliance product for an industrial material such as concrete.

The lead glass and/or the boro-silicated glass in the waste electric appliance product and waste casting sand are used as neutralizing and reforming agent, and the basicity (CaO+MgO)/(SiO2+Al2O3+Fe2O3) of the flag is held at 0.4-0.7 to prevent such problem of the steelmaking slag of developing the bulge-collapse and the pollution caused by the elution of Ca ion and to utilize for concrete aggregate and sand for sand pile, etc. Further, as a method for neutralizing, the lead glass and/or the boro-silicated glass are used too, so as to become 0.05-0.3% B2O3 and 0.4-0.7 basicity.