There is provided a power-supply circuit for supplying voltage to a load, having a power supply that generates power-supply voltage, an inverted outputting circuit having a positive voltage terminal for outputting positive voltage based on the power-supply voltage and a negative voltage terminal for outputting negative voltage generated based on the power-supply voltage and having different polarity from the positive voltage and outputting the positive and negative voltage while keeping the same direction in terms of directions of electric current flowing between the positive voltage terminal and the outside and of electric current flowing between the negative voltage terminal and the outside, a step-down output circuit for outputting predetermined step-down output voltage to the outside by connecting the positive and negative voltage terminals to the outside while switching them with a predetermined duty ratio and a step-up output circuit for supplying step-up output voltage whose absolute value is greater than that of the step-down output voltage by switching whether or not to connect the step-down output circuit to the load with a predetermined duty ratio.