A power supply unit, which is mounted in a host device for supplying power to a client device through a cable interposed therebetween, includes an output unit configured to generate a first output voltage from an input voltage. A controller is provided in the power supply to perform voltage feedback control on the output unit such that the first output voltage is maintained at a predetermined target value. Also, the power supply unit includes a first correction unit configured to correct the voltage feedback control at the controller such that the first output voltage is increased as a second output voltage finally supplied to the client device becomes lower, and a second correction unit configured to correct the voltage feedback control at the controller such that the first output voltage is increased as an output current supplied from the host device to the client device becomes larger.