Today's cosmetics market in Japan is seeing a strong demand for whitening agents from women wishing to remove pigmentations from facial skin. At the same time, we and other researchers are trying to produce useful materials (e.g., medicines and cosmetics) from the distillation remnants of shochu spirits, because the disposal of these remnants in the sea will be prohibited from 2007. In the present study, we carried out basic research for development of a cosmetic whitening agent from powdered barley shochu distillation remnants using B16-F0 melanoma cells at a safe low density of 10 mu g/mL. The findings were as follows: (1) B16-F0 melanoma cells were visibly whitened; (2) melanin production by the cells was markedly depressed; and (3) tyrosinase activity of the cells was strongly inhibited. These findings indicate the potential applicability of powdered barley shochu distillation remnants in cosmetic whitening agents.