To provide a method for treating waste by which such a problem is solved that since there is a possibility that harmful halogenated organic compounds such as dioxins or heavy metals are contained in solid waste such as the fly ash or main ash to be discharged from a waste incineration plant or the like, a method for heat-treating incineration ash in an oxygen-deficient state in a highly hermetically-sealed atmosphere is proposed however special equipment is required to keep the oxygen-deficient state and the capital investment and maintenance cost of the special equipment are high and since both of dioxins and heavy metals are contained in waste such as fly ash, it is difficult to simultaneously treat dioxins and heavy metals according to the conventional method and by which dioxins and heavy metals in waste can be treated simultaneously and waste can be efficiently treated even when waste has high heavy metal content.

The method for treating waste comprises a step of adding a compound (A component) having a dithiocarbamate group and salt (B component) obtained by reacting an amino compound with acids to waste to detoxify the waste.