A titanium dioxide composite is provided that can be stably dispersed in an aqueous solvent and easily administered into a living body, such as human, and allows elimination of the drug efficacy of a pharmaceutical compound supported thereon by light irradiation and a dispersion thereof. A composite is used in which a pharmaceutical compound is bound to titanium dioxide having photocatalytic activity through a hydrophilic polymer. The composite is stable in an aqueous solvent and easily administered into a living body, and adverse drug reactions of the pharmaceutical compound can be reduced by administering the composite into the body and irradiating the composite with a light to photoexcite the titanium dioxide to decompose the pharmaceutical compound in a region where the drug efficacy of the pharmaceutical composition is not required.
