To provide a safe waste treating method capable of performing regeneration of granular waste such as filter sand without having adverse effects on surrounding environments.

The waste treating method includes: a heating process of heating the granular waste as a material to be treated; and a regeneration process of regenerating the heated granular waste. Due to this configuration, even if the granular waste is contaminated with pathogenic organisms which might have adverse effects on human bodies, since the granular waste is heated before regenerated, the pathogenic organisms are destroyed, so as to securely prevent occurrence of a situation where the pathogenic organisms are scattered to the surrounding environments at the regeneration stage. Thus, safe and reliable waste treatment which prevents adverse effects on the surrounding environment can be achieved.