In titanium oxide crystals, nitrogen atoms are substituted for some of the oxygen sites, doped at interstitial sites of crystal lattices, or doped in grain boundaries, or a combination of these methods is employed. As a result, a chemical bond between Ti and N atoms is present in the crystals and a photocatalytic activity is exhibited by absorbing visible light. For example, Ti-O-N film with a film thickness 10 mu m or less is formed on a substrate. Thus, a photocatalytic material may be obtained which exhibits a photocatalytic activity with visible light. <IMAGE>