The invention provides titanium dioxide fine particles, wherein nitrogen and at least one element selected from carbon, hydrogen, sulfur doped in titanium dioxide by heat-treating fine particles of a material of titanium dioxide at 500.degree. C. or more and 600.degree. C. or less in a reducing gas atmosphere containing nitrogen. The titanium fine particles exhibit a high photocatalytic activity than in the conventional art by irradiating a visible light such that they exhibit an isopropanol oxidation activity induced by visible light irradiation with a wavelength of 400 nm or more and 600 nm or less with excellent stability and durability of the photocatalytic activity.