A dimming device is provided which is compatible with an increased number of types of illumination loads. A signal source (910) generates a drive signal (Sd1) according to a dimming level. A discharge part (920) includes a series circuit having a Zener diode (ZD1) and a rectifier element (D9) connected in series. The series circuit enables passage of a reverse current of the Zener diode (ZD1). In the discharge part (920), the series circuit is electrically connected between a control terminal (20) and the signal source (910) to enable the reverse current of the Zener diode (ZD1) to flow from the control terminal (20) to the signal source (910).