The protection to the cytotoxicity of 24S-hydroxycholesterol on the brain-derived cells should be useful as a new therapy of Alzheimer’s disease. In this study, we have revealed neuroprotective effect of polyphenol, especially (−)-epigallocatechin-3-gallate and (−)-epicatechin gallate on cytotoxicity of 24S-hydroxycholesterol. These results suggest the possibility of a new complementary therapy for Alzheimer’s disease.