PURPOSE: To provide a lamp lighting circuit which prevents the occurrence of hunting and the like.

CONSTITUTION: A dimming circuit 7 outputting dimming current which is changed in response to the resistance value of a variable resistor 73 every each lamp 6a and 6b, is provided, and concurrently the output current 13 and 14 of current detection circuits 5a and 5b corresponding to each lamp 6a and 6b is synthesized with dimming current 11 and 12. Based on voltage Vfa and Vfb corresponding to the aforesaid synthesized current, the drive of each chopper circuit 3a and 3b is controlled by a chopper drive control circuit 2 to make the aforesaid voltage Vfa and Vfb roughly constant. This constitution thereby prevents the occurrence of hunting and the like which is used to take place, thereby enables dimming to be stably kept on, and also enablee a range of dimming wider than a former one to be set even when an operation amplifier is used for the input stage of the chopper drive circuit.