To provide a discharge lamp using mercury vapor, capable of heating a tube end while evading leakage between the vicinity of an outer lead and a heater without lowering thermal efficiency.

One end of the heater wire of the heater 1d is connected to the outer lead 1c, and the heater wire is wound around so as to be attached to the outer tube wall on the end side of a discharge tube 1a composed of a glass tube. The other end of the heater wire is connected through power supply wiring 2 to one end of the output of an inverter power supply circuit 5 constituting the lighting circuit of a fluorescent lamp 1. Thus, the heater 1d is inserted serially to a route through which a lamp current flows.