To provide a power supply unit which outputs a plurality of dc voltages, wherein a malfunction of a device which receives the voltages from the power supply unit is prevented by eliminating startup time differences of a plurality of dc voltage sources, and to provide an electric circuit mounting the power supply unit.

In the power supply unit, the second dc voltage source can be started simultaneously with startup of the voltage of the first dc voltage source, by which the startup time differences of dc voltage sources causing the malfunction of the device receiving the voltages from a plurality of dc voltage sources are eliminated, and the malfunction of the device is prevented. Moreover, the electric circuit does not cause the malfunction of the device by connecting an output of the first dc voltage source and an output of the second dc voltage source of the power supply unit to the same device.