To provide a photocatalyst with high catalytic activity.

This photocatalyst includes a phototransmitting particle with pores formed in the surface which is uniformly covered with titanium dioxide having photocatalytic function. In addition, the specific surface of this photocatalyst is 600 to 1,500 m2/g. The specific surface is preferably 800 to 1,500 m2/g and is more preferably 1,000 to 1,500 m2/g. Besides, the phototransmitting particle is preferably of mesoporous silica, and the film thickness of the titanium dioxide layer is preferably 4 to 30 . and the titanium dioxide is more preferably covered by atomic layer accumulation process.