The invention provides a photocatalyst composition and a photocatalyst paint composition capable of forming photocatalyst paint body. The photocatalyst composition, when irradiated by visible light in the air, shows excellent antimicrobial activity and antiviral activity, at the same time, inhibits discoloration resulting from visible light irradiation, and can be made into an antiviral agent and an antibacterial agent. The photocatalyst composition contains at least one bivalent copper compound represented as the following general formula and a photocatalyst. The general formula is Cux(OH)y(SO4)z, wherein neither of x, y, or z is equal to 0 and x, y, and z satisfy a relation of 2x=y+2z and are positive integers. Furthermore, the antiviral agent and the antibacterial agent contain the photocatalyst composition. The photocatalyst paint composition contains the photocatalyst composition, an adhesion agent, and a dispersion medium.
