POWER SOURCE DEVICE

A power source device includes a step-up circuit, a diode for backflow prevention, and an electrolytic capacitor. The step-up circuit is connected to a power source on an input side thereof and is connected to a first load and a second load in parallel on an output side thereof. The diode for backflow prevention is connected between the step-up circuit and the first load. The electrolytic capacitor is connected between the diode for backflow prevention and the first load.