Filament lamps whose individual filament coils can be set to specific temperatures in filament lamps that are supplied with electric power independently and to provide a heat treatment device of the light irradiation type that uses said lamps. Inside of a light emitting tube of each lamp, which has the hermetically sealed portions at each end, are multiple filament modules which have been made by linking pairs of leads which supply electrical power to both ends of coiled filaments and individual filaments that are placed so that they extend along the axis of the light emitting tube. In the electrically connected filament lamps, whose individual leads are connected to the respective electrically conductive material placed in the hermetically sealed portions, at least one of the individual filaments is made up of a single wire and at least two are made up of bundled wires with the single wire being located between the bundled wires.