An electric power supply system comprising: a common power source which includes a storage cell, and is configured to supply a power to the storage cell from buildings (B1-B4) and from the storage cell to the buildings (B1-B4) via a local power grid (Pd) installed in a specific area including the buildings (B1-B4); a distributed power source provided in at least a part of the buildings (B1-B4) in the area and configured to supply a power to said at least some of the buildings (B1-B4) and supply a surplus power to the common power source; and a first power meter provided in each of the buildings (B1-B4) and configured to measure an amount of a power supplied from a commercial power source, characterized in that the electric power supply system further comprises: a second power meter provided in each of the buildings (B1-B4) and configured to measure amounts of power supplied from and to the common power source via the local power grid (Pd); and a distribution control device which is configured to distribute a power from the common power source to the area on the basis of the amounts of power measured by the first power meter and the second power meter, the local power grid (Pd) is configured to serve as a grid connection of a power system of the commercial power source and the respective buildings (B1-B4); and the common power source has a function of storing a power in the storage cell which is received via the local power grid (Pd) from the buildings (B1-B4) and supplying a power to the buildings (B1-B4) from the storage cell via the local power grid (Pd), and the distribution control device is configured to perform a management so that the amount of the power supplied to the common power source from each of the buildings (B1-B4) and measured by the second power meter and the amount of the power supplied to each of the buildings (B1-B4) from the common power source and measured by the second power meter are offset within a predetermined period, wherein the management includes supplying a power from the common power source to a building (B1, B2, B3 or B4) when the amount of the power supplied from the commercial power source measured in a unit period by the first power meter of the building (B1, B2, B3 or B4) is equal to or greater than a prescribed value and returning a power to the common power source from the building (B1, B2, B3 or B4) when the amount of the power supplied from the commercial power source measured in the unit period by the first power meter of the building (B1, B2, B3 or B4) is less than a return value, the return value being set to be a value lower than the prescribed value. a common power source which includes a storage cell, and is configured to supply a power to the storage cell from buildings (B1-B4) and from the storage cell to the buildings (B1-B4) via a local power grid (Pd) installed in a specific area including the buildings (B1-B4); a distributed power source provided in at least a part of the buildings (B1-B4) in the area and configured to supply a power to said at least some of the buildings (B1-B4) and supply a surplus power to the common power source; and a first power meter provided in each of the buildings (B1-B4) and configured to measure an amount of a power supplied from a commercial power source, a second power meter provided in each of the buildings (B1-B4) and configured to measure amounts of power supplied from and to the common power source via the local power grid (Pd); and a distribution control device which is configured to distribute a power from the common power source to the area on the basis of the amounts of power measured by the first power meter and the second power meter, the local power grid (Pd) is configured to serve as a grid connection of a power system of the commercial power source and the respective buildings (B1-B4); and the common power source has a function of storing a power in the storage cell which is received via the local power grid (Pd) from the buildings (B1-B4) and supplying a power to the buildings (B1-B4) from the storage cell via the local power grid (Pd), and the distribution control device is configured to perform a management so that the amount of the power supplied to the common power source from each of the buildings (B1-B4) and measured by the second power meter and the amount of the power supplied to each of the buildings (B1-B4) from the common power source and measured by the second power meter are offset within a predetermined period, wherein the management includes supplying a power from the common power source to a building (B1, B2, B3 or B4) when the amount of the power supplied from the commercial power source measured in a unit period by the first power meter of the building (B1, B2, B3 or B4) is equal to or greater than a prescribed value and returning a power to the common power source from the building (B1, B2, B3 or B4) when the amount of the power supplied from the commercial power source measured in the unit period by the first power meter of the building (B1, B2, B3 or B4) is less than a return value, the return value being set to be a value lower than the prescribed value.