The present invention obtains an inexpensive material with a photocatalytic function. A photocatalyst is obtained by halogenation of a glass fiber with silicon dioxide in the composition thereof. Molten quartz soda lime glass alkali free glass or borosilicate glass can be used for the glass. Hydrofluoric acid hydrochloric acid and hydrobromic acid can be used in the hydrohalogen acid but hydrofluoric acid is most desirable. The form may be granular fibrous or sheet form. The glass exhibits a photocatalytic function even with non ultraviolet visible light and has a water repelling effect. This glass is capable of decomposing organic matter and the plate form is used as window glass for buildings and as window glass for vehicles and other transportation devices. The fibrous form is used as a filter for air suction and discharge devices.
