This invention provides a contamination-resistant float glass showing even quality in durability and its good quality sufficienty. The film for contamination-resistance is formed only on the top-side surface of a float glass. The surface, free from tin diffused from a float bath, can be identified by ultraviolet irradation. A solution including a chemical adsorbent like fluoroalkyltrichlorosilane is applied to the top-side surface by a roller coater. The adsorbent can be prevented from hydrolyzing with dry air around the coating portion of the coater. Surplus solution can be removed with dry air blown on the surface to make the contamination-resistant property and the appearance better. The chemical adsorbent is bonded to the surface via a siloxane bond to form a thin film. The contamination-resistant float glass is installed in the front door of an apparatus like a toaster oven with the film facing the inside of the oven. The film on the top-side surface shows higher contact angles than that on the bottom-side surface in durability tests.