A power supply system, comprising: a power conversion device that is installed in a facility of a consumer and has an independent terminal group for extracting power during a period in which power reception from a power grid is not possible; a switching unit that is connected between the power grid and power conversion device and a load, selects a first state in which the load is connected to the power grid during a period in which power reception from the power grid is possible, and selects a second state in which the load is connected to the independent terminal group during the period in which power reception from the power grid is not possible; a distributed power source which is connected to an electrical pathway connecting the switching unit to the load and for which a reverse flow of power to the power grid is prohibited; a current sensor that monitors a current flowing between the distributed power source and the switching unit in the electrical pathway; a control unit that monitors a direction in which power that is output from the distributed power source is supplied, by using an output of the current sensor; characterized in that the power supply system further comprises a plurality of branch breakers connected to the electrical pathway; and a controller for controlling opening/closing of the plurality of branch breakers, wherein in response to an instruction from the control unit, the distributed power source is configured to adjust the power to output, in such a manner that power flowing from the distributed power source toward the switching unit is not generated, wherein the electrical pathway includes a principal electrical pathway for connecting the switching unit to the plurality of branch breakers, and a plurality of branch electrical pathways for connecting a plurality of devices functioning as the load to the plurality of branch breakers respectively, the control unit is configured to receive input of a value corresponding to an output of the current sensor, and the power supply system further comprises a regulator for adjusting a ratio between a value of a current passing through the electrical pathway and the value input to the control unit, the current sensor comprises a plurality of current sensors that are disposed in the electrical pathway and have sensitivities different from one another, and the regulator is configured to adjust the ratio by allowing the control unit to use an output of a current sensor selected from among the plurality of current sensors. a power conversion device that is installed in a facility of a consumer and has an independent terminal group for extracting power during a period in which power reception from a power grid is not possible; a switching unit that is connected between the power grid and power conversion device and a load, selects a first state in which the load is connected to the power grid during a period in which power reception from the power grid is possible, and selects a second state in which the load is connected to the independent terminal group during the period in which power reception from the power grid is not possible; a distributed power source which is connected to an electrical pathway connecting the switching unit to the load and for which a reverse flow of power to the power grid is prohibited; a current sensor that monitors a current flowing between the distributed power source and the switching unit in the electrical pathway; a control unit that monitors a direction in which power that is output from the distributed power source is supplied, by using an output of the current sensor; characterized in that the power supply system further comprises a plurality of branch breakers connected to the electrical pathway; and a controller for controlling opening/closing of the plurality of branch breakers, wherein in response to an instruction from the control unit, the distributed power source is configured to adjust the power to output, in such a manner that power flowing from the distributed power source toward the switching unit is not generated, wherein the electrical pathway includes a principal electrical pathway for connecting the switching unit to the plurality of branch breakers, and a plurality of branch electrical pathways for connecting a plurality of devices functioning as the load to the plurality of branch breakers respectively, the control unit is configured to receive input of a value corresponding to an output of the current sensor, and the power supply system further comprises a regulator for adjusting a ratio between a value of a current passing through the electrical pathway and the value input to the control unit, the current sensor comprises a plurality of current sensors that are disposed in the electrical pathway and have sensitivities different from one another, and the regulator is configured to adjust the ratio by allowing the control unit to use an output of a current sensor selected from among the plurality of current sensors.