To provide a stabilized power source and an image forming device in which a stabilized output small in voltage difference such as 3.3V can be obtained from a low voltage such as 5V.

The 5V is supplied from a power source for driving a laser diode for exposing an image to the collecter of a transistor Q101, and 24V is supplied from a power source for driving a motor for feeding paper and a scanner motor to the power supply terminal of an operating amplifier. The emitter voltage, that is, output voltage of the transistor Q101 is compared with the reference voltage of a Zener diode ZD101 by an operating amplifier IC101, and the compared output is supplied to the transistor Q101, and the output voltage is stabilized to 3.3V. Even when the input of the transistor Q101 is set to be low as 5V, and an input/output difference is set to be low as almost 1.7V, 24V is supplied to the operating amplifier IC101 being an error amplifier so that a stable operation can be attained.