To provide a dimmer circuit that can freely set the emission intensity of a light emitting element by using a comparatively small number of additional components.

Normally, a terminal A is set to a Lo level and a transistor Tr2 is turned off but a first transistor Tr1 is turned on by a base current flowing through R3. As a result, a current flows to LED1, R1, a diode D1, and Tr1 from a positive pole of a power source, and the LED 1 emits the light of intensity regulated by a resistor R1. When dimmer controlling, the terminal A is set to a Hi level and Tr2 is turned on, but Tr1 is turned off by a voltage drop caused by R3. As a result, the current flows to LED1, R3, and Tr2 from the positive pole of the power source, and the LED1 emits the light of intensity dimmer-controlled by R3.