NOVELTY - The variation estimation method involves performing (S1) measurement of weather data or electric power generation output data in a presumed object area. The weather data or electric power generation output data are used. The standard deviation as a finger mark or a parameter of the variation magnitude of the electric power generation output is calculated (S2) in a measurement point by a natural energy type distributed power supply. The parameter of the variation magnitude of the electric power generation output and the variation magnitude of the average output are used.    USE - Method for estimating the variation magnitude of total output of a natural energy type distributed power supply group, such as a photovoltaic power generation or a wind power generation.    ADVANTAGE - The variation estimation method involves performing measurement of weather data or electric power generation output data in a presumed object area, and thus ensures small calculation load for the apparatus, simply estimates the variation magnitude of the total output of natural energy type distributed power supply from small amount of data, reduces the expense and the effort concerning the data collection, performs the estimation process without using the installation of the special computer device improves the necessity to report speedily the variation tendency of total output, and improves the versatility of the variation estimation technique for the total output of the natural energy type distributed power supply group.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a variation estimation apparatus for estimating the variation magnitude of total output of a natural energy type distributed power supply group; and    (2) a variation estimation program for estimating the variation magnitude of total output of a natural energy type distributed power supply group.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of variation estimation method. (Drawing includes non-English language text).    Performing measurement of weather data or electric power generation output data in a presumed object area (S1)    Calculating standard deviation as a finger mark or a parameter of the variation magnitude of the electric power generation output (S2)    Calculating average correlation between the variations of the electric power generation output of the natural energy type distributed power supply (S3)    Estimating parameter of the smoothing effect of the natural energy type distributed power supply by using average correlation (S4)    Estimating the magnitude of the variation of an average output by numerical formula (S5)