For providing a lamp lighting device and a filament lamp wherein a wire breakage of the filament lamp can be detected without an excessive consumption of power while the device as a whole is not enlarged, a filament lamp is provided comprising a light emission tube having at least one sealing portion and in the interior of which at least one filament is arranged, internal leads connected to both ends of said filament, metal foils for power supply provided in said at least one sealing portion of the light emission tube and connected to said internal leads, and external leads connected to said metal foils for power supply; wherein a metal foil for detection is provided in said sealing portion and is connected to one of a said internal lead and a said metal foil for power supply, and an external detection lead is provided at said metal foil for detection.