To provide an insulated power supply device which is made compact in size.

This insulated power supply device generates a plurality of desired dc voltages from dc voltage, and has an ac voltage generator which generates ac voltage from dc voltage based on a control signal, the first transformer which ac voltage from the ac voltage generator is input, a plurality of second transformers which ac voltage outputted by the first transformer is inputted. The device also has a rectifying and smoothing circuit provided for each of the second transformers. In this circuit ac voltage, outputted by the second transformer, is inputted, rectified and smoothed, and outputted as a desired dc voltage. The device has an insulator which ac voltage outputted by the first transformer is inputted and a control signal, based on the ac voltage is insulated and provided to the ac voltage generator.