To provide an inverter for lighting a cold-cathode tube capable of lighting a cold-cathode tube at constant brightness.

An inverter for lighting a cold-cathode tube 10 is constituted with a piezoelectric transformer 17; a voltage control oscillating circuit 11; an oscillating frequency control circuit 16 for controlling oscillating frequency in the voltage control oscillating circuit 11; a driving circuit 12 for driving the piezoelectric transformer 17; a dimmer circuit 13 for controlling the dimmer; a cold-cathode tube current detecting circuit 15 for detecting tube current of a cold-cathode tube; a protecting circuit 19 for protecting the piezoelectric transformer 17 from the change in load impedance; and a temperature compensation circuit 25 for controlling brightness in accordance with the change of the ambient temperature.