We have examined photocatalytic reactions sensitized by composite particles consisting of titanium oxide, and perovskite-type titanate containing alkaline earth elements. The photocatalytic activities of perovskite-type oxides SrTiO₃, BaTiO₃, and CaTiO₃ are fairly weaker than that of anatase-type titanium dioxide TiO₂; however, in photobleaching of methylene blue under irradiation with Xe discharge light, the composite particles with TiO₂ exerted photocatalytic activity several times that of TiO₂ alone. Especially, the composite powder containing 30 mass% SrTiO₃ exhibited the highest photocatalytic activity. The results imply the flow of photogenerated electrons and holes through the heterogeneous junctions in the composite particles. The photocatalytic activity of the composite powder was decreased when the SrTiO₃ was doped with Ga and Y, presumably because of recombination of the photogenerated charges via oxygen vacancies created by the doping.