A power management and control system which comprises a natural energy power generation apparatus and a storage battery adapted to charge and discharge part of power generated in the natural energy power generation apparatus, wherein the power management and control system is configured to combine total generation power from the natural energy power generation apparatus and power to be supplied from the storage battery to supply constant output power to a power network, the power management and control system having power transmission plan calculating means which is adapted to receive power generation amount prediction data predicting a power generation amount in each unit time in the natural energy power generation apparatus, and is adapted to calculate a plan for power transmission to the power network to keep a power storage amount of the storage battery in a designated range, based on the power generation amount prediction data, the power management and control system is configured to control a charge and discharge amount of the storage battery in accordance with an actual power generation amount with power generation output varying based on a fixed power transmission plan which is fixed with reference to a power transmission plan calculation result by the power transmission plan calculating means to supply constant output power to the power network in accordance with the fixed power transmission plan, comprising: a power generation control system adapted to control the generation power of the natural energy power generation apparatus based on a magnitude of present chargeable power which is received from the storage battery in real time, wherein the power management and control system further comprises a power supervisory control unit which is adapted to compare a generation power output upper limit target candidate value that depends on power which can be charged in and discharged from the storage battery, and a rated output value of the natural energy power generation apparatus, and is adapted to control the power generation control system with the generation power output upper limit target candidate value as a power generation output upper limit target value, when the rated output value of the natural energy power generation apparatus is greater than the generation power output upper limit target candidate value, wherein the power generation output upper limit target candidate value is obtained from calculation of (power transmission plan power + station power consumption + chargeable power) × coefficient (value not larger than 1). a power generation control system adapted to control the generation power of the natural energy power generation apparatus based on a magnitude of present chargeable power which is received from the storage battery in real time, wherein the power management and control system further comprises a power supervisory control unit which is adapted to compare a generation power output upper limit target candidate value that depends on power which can be charged in and discharged from the storage battery, and a rated output value of the natural energy power generation apparatus, and is adapted to control the power generation control system with the generation power output upper limit target candidate value as a power generation output upper limit target value, when the rated output value of the natural energy power generation apparatus is greater than the generation power output upper limit target candidate value, wherein the power generation output upper limit target candidate value is obtained from calculation of (power transmission plan power + station power consumption + chargeable power) × coefficient (value not larger than 1).