A distributed power supply system of the present invention comprises a distributed power supply apparatus (4) for supplying electric power to a customer load (2) interactively with a commercial electric power utility (1); an internal load (7) supplied with electric power from the commercial electric power utility; a current sensor (5a, 5b) for detecting a magnitude of a current and a direction of the current, the current being in a location closer to the commercial electric power utility than the internal load and the customer load; and a controller (8); wherein in a state where the distributed power supply apparatus 84) is not generating the electric power, the controller causes the internal load (7) to actuate, performs determination control as to an installation state of the current sensor (5a, 5b) plural times based on a value detected by the current sensor, and performs the determination control in such a manner that at least one of plural intervals at which the determination control is performed is set to an interval other than an integral multiple of another interval of the plural intervals.