The PD device comprises a primary-side controller configured to control an input current of a DC/DC converter disposed between an input and an output, and a secondary-side controller connected with AC coupling to the output, and configured to feed back electric power information of the output to the primary-side controller. The primary-side controller varies an output voltage value and an available output current capacity of the DC/DC converter by controlling the input current on the basis of the electric power information fed back from the secondary-side controller. The primary-side controller can change an overpower detecting set value in accordance with the target equipments connected to the output, thereby executing the power change of the DC/DC converter.