To provide a discharge lamp lighting device which can detect end of life of a discharge lamp without using an insulating means.

When an emitter of any filaments FL1a, FL1b, FL2a, FL2b is lost because of an end of life of fluorescent lamps FL1, FL2, half-wave discharge occurs by generation of discharging deviation. Because lamp current contains direct current component, direct current electricity does not flow at capacitors C11 and C12, then voltage is generated at impedance elements Z2 and Z3. The voltage generated at the impedance elements Z2 and Z3 is reverse potential against diodes D5 and D6. Since higher voltage of either impedance elements Z2 and 23 is inputted to a control means by the diodes D5 and D6, end of life of either fluorescent lamps FL1 or FL2 can be judged whichever way half-wave discharge is generated. A control means 18 controls a transistor Q1 through a driving means 19, to stop or drop output of an inverter circuit 16.