Light-storing photocatalyst was prepared by combining long afterglow phosphor with TiO2 photocatalyst film, and bactericidal effect of this material on E.coli was investigated. TiOz shows high bactericidal ability under irradiation of light source and can decompose bacterial cell completely, but can not function in the darkness. The long afterglow phosphor can supply light for TiOz film after irradiation source is cut off, and hence E.coli can be killed by the light-storing photocatalyst even in the dark. This light-storing photocatalyst can be irradiated intermittently while maintaining photocatalyst activity all the time.