Here we demonstrate that photoactive titania (titanium dioxide) nanoparticles are successfully hybridized with an optimized amount of mesoporous silica (silicon dioxide) nanoparticles to realize drastic improvement of photocatalitic activity of the titania nanoparticles. Various types of mesoporous silica/titania composites are prepared by changing the amounts of doped mesoporous silica. Low-angle XRD patterns and N2 adsorptiondesorption isotherms reveal that the original mesostructures and pore sizes of mesoporous silica nanoparticles are well maintained even after hybridization with the titania nanoparticles. From SEM and TEM observation, it is confirmed that both the nanoparticles are homogeneously dispersed in the composite matrix. The obtained mesoporous silica/titania composites show excellent photocatalytic activity in the decomposition of methylene blue (MB), in comparison with titania nanoparticles without mesoporous silica. By hybridization with mesoporous silica, the photogenerated radicals from titania surfaces can efficiently react with many MB molecules captured inside the mesopores.