To develop such a material that the photocatalytic effect per unit area of the material is heightened by depositing/fixing a large quantity of a photocatalyst on the surface of a magnesium alloy.

This magnesium metallic material having a photocatalytically active surface is manufactured by pretreating magnesium alloy materials having various shapes mechanically or chemically so that the surface of each of the magnesium alloy materials is changed from a two-dimensional surface to a three-dimensional surface and the surface area is increased, anodizing the surface area-increased magnesium alloy material by non-spark discharge to form a transparent or translucent porous film having many minute pores and metallic luster and filling the minute pores of the film with the photocatalyst.