To provide a dust-collecting device for an electric furnace with a ring hood capable of preventing the outflow of gas or smoke from a tapping port while suppressing heat loss in the furnace in a furnace lid closing state upon dissolution.

An opening 2A at the center of the ring hood 2 of the dust- collecting device is widely opened so that the lid 4 of the furnace 1 advances from above the hood 2 to be reached to the opening 5 of the furnace 1, thereby allowing the opening 5 to be directly closed by the lid 4.