PURPOSE: To provide small, highly economical constitution and to readily adjust color temperatures by controlling electric discharge lamps of different color temperatures via two inverters connected in parallel such that output pulse signals have their on-duty periods made variable by a common control circuit.

CONSTITUTION: Inverters 1d, 1e connected in parallel to an AC power supply Vac via a rectifier D. B. are driven by respective pulse signals (d), (e) with variable on-duty periods which a common control circuit 2d outputs. High and low color temperature electric discharge lamps, 3d, 3e, respectively, for connection to the respective intervers 1d, 1e, are dimmed. Therefore, the lighting system allows easy adjustment of color temperatures with its constitution that is smaller and higher economy than it would be if each inverter is provided with its own control circuit.