<p>A method of producing flat glass, capable of improving surface smoothness in a movement direction of the flat glass and preventing lines from occurring on the flat glass. Supporting bodies (12) are arranged in such a way that the bodies at least do no move in the direction parallel to the direction of movement of a glass ribbon (13). A fixed floor (15) is used, and in the floor (15), grooves (12B) for allowing steam formed of an evaporated steam film-forming agent to escape are individually formed between adjacent supporting bodies (12). An amount of steam to be allowed to escape from each of the grooves (12B) is adjusted in accordance with glass temperature distribution in the movement direction of the glass ribbon (13) moving on the fixed floor (15).</p>
