Provided is a titanium oxide dispersion liquid that has dispersibility and dispersion stability both at superior levels and, when applied and dried, can form a photocatalyst coating film capable of rapidly developing excellent photocatalytic activity. The titanium oxide dispersion liquid according to the present invention includes titanium oxide particles (A), a dispersing agent (B), and a solvent (C). The titanium oxide particles (A) support a transition metal compound. The dispersing agent (B) includes a poly(acrylic acid) or a salt thereof. The poly(acrylic acid) or a salt thereof in the dispersing agent (B) preferably includes a poly(acrylic acid) alkali metal salt. The poly(acrylic acid) or a salt thereof in the dispersing agent (B) preferably has a weight-average molecular weight of from 1000 to 100000.