A metal-oxide layer exhibiting a photocatalytic activity function is formed on the surface of an inorganic architectural material, such as external wall material, roofing material, internal wall material, flooring material, and ceiling material, including glass, tile, concrete, stone, metal, and the like, so as to provide the property of deodorizing a space coming in contact with the architectural material, and antimold, antisoiling properties, and ultraviolet-ray absorbency of the surface of the architectural material, as well as the long-term maintenance of these properties. Preferably, the metal-oxide layer is formed by fixing a metal-oxide thin film on the surface of the architectural material. Alternatively, the metal-oxide layer is formed as an architectural material in which the surface thereof and its vicinity are mainly formed of a metal mixture including a metal oxide, such as titanium oxide, and palladium for improving photocatalytic activity, or a metal mixture including a metal constituting the metal oxide, such as titanium, and a composite of a second metal, while its inner portion is substantially formed of a metal mixture including titanium or a composite of titanium and palladium, the surface and its vicinity as well as the inner portion being formed continuously. As a method of manufacturing the latter architectural material, a metal mixture, i.e., an alloy, of titanium and a metal for improving photocatalytic activity, such as palladium, is fabricated, and after the alloy is processed into a desired shape, the processed alloy is subjected to oxidation treatment.