The power supply apparatus including a high-voltage generation unit generating a DC voltage VA includes a Zener diode that drops the DC voltage VA to a DC voltage VB, a resistor connected to a line to which the DC voltage VA is output, and a voltage divider that generates a DC voltage VC by dividing the DC voltage VA with the resistor, and the voltage divider adjusts the DC voltage VC such that the potential difference between the DC voltage VB and the DC voltage VC is within a predetermined range.