PURPOSE: To improve the catalytic activity of a photocatalyst by forming a thin film composed of a mixture of a rutile type TiO2 and SnO2 having a specific crystal diameter on the surface of a base material.

CONSTITUTION: A suspension A is prepared by adding 4-6wt.% TiO2 sol into an ammonia aq. solution adjusted to pH11. A suspension B is prepared by adding 10wt.% SnO2 sol having 0.01μm crystal diameter into the ammonia aq. solution adjusted to pH11 in another vessel. The suspension A and B are mixed with each other in a prescribed ratio, applied on the surface of a tile base material by spray coating method and fired at 850°C for 2hr after drying to obtain a sample. That is, in the member obtained by forming the photocatalyst thin film on the surface of the base material, sufficient denseness and the film strength of TiO2 are attained by treating at a firing temp. that TiO2 component in the photocatalyst thin film is converted into rutile type. In this case, the photocatalytic activity of the photocatalyst thin film is improved by existing SnO2 having <0.01μm crystal diameter other than rutile type TiO2.