Abstract: A flat cable type extension wire including a flat cable connected between an electric plug and a socket is disclosed. The flat cable is composed of a first wire group and a second wire group each of which is composed of a plurality of parallelly arranged conductive wires. One end of each conductive wire of the first wire group is connected with a first plug terminal of the plug, while the other end of the conductive wire is connected to a first conductive contact of the socket. One end of each conductive wire of the second wire group is connected with a second plug terminal of the plug, while the other end of the conductive wire is connected to a second conductive contact of the socket. The first wire group and the second wire group are isolated from each other by an insulative section with a certain width. The extension wire is further connected with a winding mechanism for winding the flat cable into a housing.