Abstract: The present invention relates to a slag discharge door device for an electric furnace, wherein slag is prevented from flowing out via a slag discharge port by making a discharge control door body move up and down to and from the upper surface of a supporting body where slag is discharged by flowing to the upper surface, and the discharge of slag is controlled, such that during steel-making work in the electric furnace, the outflow of slag is prevented and heat losses are reduced, the efficiency of arc heat due to the formation of foamed slag is increased, and valuable metals are recovered from the molten slag thereby increasing the percentage of molten steel recovered.