The sterilizing effect of zeolite supported by metal-ion on washing water was investigated experimentally. Silver, zinc and copper were used for the metal-ion and these zeolite materials were added to the washing water together with the surface active agent (sodium dodecylbenzenesulfonate : DBS). The number of living bacteria in the washing water was counted before and after washing. As a result, by using the zeolite supported by metal-ion, the living bacteria could not be observed in the used washing water even though the content of zeolite was fairly small at 0.05wt%. In the case of sodium zeolite, the sterilizing ability of DBS deteriorated. In addition to the above examinations, the sterilizing effect of zeolite on used bath water was examined. The used bath water with bacteria of 5.7 × 10⁵/ml was applied to the washing together with the zeolite supported by metal-ion of 0.05wt%. The observation experiment suggests that no bacteria exists in the water after washing. It is concluded here that the metal-ion acts effectively as a sterilizer during the washing process and the used bath water can be applied to the washing water using the zeolite supported by matal-ion.