Provided is a power source device which has a load-following function. This power source device is provided with: a distributed power source that outputs power; and a control unit that controls output power by the distributed power source. The control unit obtains an evaluation function including the operation history of the power source device, and sets an output condition for the power source device on the basis of the evaluation function and a load-following response characteristic. When a detector, which is configured to detect a forward current flow and a reverse current flow with respect to a system to which the power source device is connected, detects the forward current flow or the reverse current flow, the control unit controls the load-following on the basis of the output condition and supplies the power from the distributed power source.
