PURPOSE: To enable an illumination circuit using an incandescent lamp to perform light adjustment without any special touch by providing an oscillation circuit for detecting increase in the electrostatic capacity of a detector caused by the approach of a part of a human body to the detector.

CONSTITUTION: Caused by the approach or separation of a human body or the like to or form a detector 1, increase in the electrostatic capacity of the detector 1 changes the oscillation output of an oscillation circuit 2 so as to operate a transistor 4 through the current control base resistance 3 thereof. An output obtained from a photocoupler 5 used to cut off the power supplies for a detect section and a light adjustment drive section in the circuit serves as the control input signal of a touch control light adjustment IC 7 on the basis of an output pulse width generated according to an approach time. A control output from the touch control light adjustment IC 7 controls the flow angle of a TRIAC 8. Therefore, light can be adjusted by specifying the average value of the current of an electric lamp 9 to be controlled.