Disclosed is a grid interconnection device that converts electric power from a power supply device into predetermined alternating-current power, and interconnects the power supply device to a power distribution system. The grid interconnection device includes a detector that detects islanding of the power supply device, and a receiver that receives power failure information including local area information indicative of an area in which a power failure occurs, through a predetermined transmission path. The detector enhances detection sensitivity for the islanding when the received power failure information includes the local area information indicative of a different area from the area to which the power distribution system belongs.