NOVELTY - The apparatus (100) has an initial demand/supply plan creating section which creates an initial demand/supply plan of controllable electric power source (1) in an electric power system. A demand/power generation amount probability density distribution creating section which creates probability density distribution of demand and natural energy electric power generation output amount at every predetermined processing time. An economic load dispatch calculating section calculates output allocation to create prediction distribution of power generation output of controllable electric power source.    USE - Electric power demand/supply planning apparatus for displaying electric power demand/supply plan for electric power system into which natural energy electric power source such as solar power generation and wind power generation are introduced.    ADVANTAGE - As the economic load dispatch calculating section calculates an output allocation to create prediction distribution of power generation output of the controllable electric power source and the display section displays the prediction distribution of the power generation output of the controllable electric power source, the displayed prediction distributions in which a fluctuation of natural energy electric power source output amount is simulated more realistically so that a user can easily have a grasp and thus the user appropriately evaluates the electric power demand/supply plan for the electric power system into which a natural energy electric power source is introduced.    DETAILED DESCRIPTION - A display section displays the prediction distribution of the power generation output of the controllable electric power source. The natural energy electric power source introduced in electric power system is based on a demand predicted value a predicted value of a natural energy electric power generation output amount and electric power source equipment data. An INDEPENDENT CLAIM is included for method for displaying electric power demand/ supply plan.    DESCRIPTION OF DRAWING(S) - The drawing shows an explanatory view illustrating a configuration of the electric power system into which natural energy electric power source is introduced.    Controllable electric power source (1)    Solar power generation equipment (2)    Wind power generation equipment (3)    Electric power distribution system (20)    Electric power demand/supply planning apparatus (100)