To search a material design based on a new principle for more enhancing the effect of a photocatalyst than conventional levels.

A material structure in which two different kinds of photocatalysts (photocatalyst I and photocatalyst II) are brought into contact with each other is set. When either one or both of the lower limit electric potential of a transmission band or the upper limit electric potential of a valence band between the photocatalyst I and the photocatalyst II are the same or near, active electrons or holes generated by photoexcitation can be moved between the photocatalyst I and the photocatalyst II, thereby permitting to enhance the effect of the photocatalyst. The present invention was proved from experimental samples on the basis of the principle.