Provided is a power supply apparatus including a low pass filter that receives an output voltage of a current output section and allows a low frequency component with a frequency lower than a preset cutoff frequency to pass through; an excess voltage restricting load section that consumes an excess voltage restricting current, which is at least a portion of the output current from the current output section, when a load is turned on; and an excess voltage restricting control section that keeps the excess voltage restricting load section turned off when the output voltage of the current output section is less than an upper reference voltage, which is obtained by adding together a voltage output by the low pass filter and a preset upper offset voltage.