Light-emitting elements disposed on a light-emitting display panel are driven by constant currents, and the forward direction voltages of the light-emitting elements are obtained by a sampling/holding circuit. Then, the voltage output from a drive voltage source composed of a DC-DC converter is controlled by the forward direction voltages obtained by the sampling/holding circuit. For example, when the light-emitting display panel starts to be driven for light emission or when the light emission luminance of the light-emitting display panel that is being driven for light emission is to be increased, a control signal is sent from a light emission control circuit to a voltage forcibly changing circuit which supplies an output voltage increase command to the PWM circuit of the drive voltage source. With this arrangement, the rising-up property of the light-emitting display panel and the following property of luminance can be improved.