Abstract: This invention relates to an optical filter made of inorganic material for green light which transfers green light and absorbs all of the other colored lights by sticking an inorganic mixture powder pasted by mixing with screen oil on a glass substrate and firing it. The mixture includes transparent glass powder and oxides of cobalt and either of chrome and a combination of aluminum and chrome. The contrast of a picture displayed on a display device can be substantially increased by reducing the reflection of incident ambient light without the reduction of brightness on account of the application of the above optical filter onto the displaying screen.