To provide a fluorescent lamp life determining device, a fluorescent lamp life determining method and an inverter device for the fluorescent lamp, by which a last stage of the fluorescent lamp life can be accurately determined.

When a switch SW3 is turned on, a series circuit of a choke coil L3 and an secondary winding n3 of an inverter transformer T1 is short- circuited by a diode bridge DB1, and tube current in a fluorescent lamp FL1 gradually increases. If a filament of the fluorescent lamp is deteriorated, the tube current slowly and gradually increases. Therefore, a time required for the tube current to exceed a designated value from when short-circuited by the diode bridge DB1 is measured by a timer 1, and it is detected by a life determining part 28 that the time exceeds the designated time, in order to determine a last stage of its life.