A power generation amount prediction apparatus for predicting a power generation amount at a power plant that performs power generation by use of renewable energy, the power generation amount prediction apparatus comprises: a model generation unit that is configured to generate a plurality of mathematical models of the power generation amount of the power plant in regard to a plurality of model generation times based on a weather track record and an output power track record in regard to the power plant; a similar track record data extraction unit that is configured to obtain a weather track record similar to weather prediction data and a corresponding output power track record as similar track record data; a model accuracy calculation unit that is configured to calculate accuracy of each of the plurality of mathematical models of the model generation unit in a weather condition similar to the weather prediction data; a model selection unit that is configured to select a mathematical model to be used for the prediction by using the accuracy of each of the models; and a model output power prediction unit that is configured to predict the power generation amount of the power plant by using the selected mathematical model, wherein the similar track record data extraction unit is configured to extract the weather track record similar to the weather prediction data, to extract an output power track record at a time of the weather track record stored at an output power track record database, and thereby obtain the weather track record and the output power track record in combination, in order to calculate the power generation amount with high accuracy even when an amount of the track record data of the generator power generation amount is insufficient or an amount of weather track record data similar to a weather prediction result is small, characterized in that the model generation unit is configured to obtain the mathematical model by adding a characteristic and an installation condition of the power plant to a primary mathematical model of the power plant generated based on the weather track record and the output power track record. a model generation unit that is configured to generate a plurality of mathematical models of the power generation amount of the power plant in regard to a plurality of model generation times based on a weather track record and an output power track record in regard to the power plant; a similar track record data extraction unit that is configured to obtain a weather track record similar to weather prediction data and a corresponding output power track record as similar track record data; a model accuracy calculation unit that is configured to calculate accuracy of each of the plurality of mathematical models of the model generation unit in a weather condition similar to the weather prediction data; a model selection unit that is configured to select a mathematical model to be used for the prediction by using the accuracy of each of the models; and a model output power prediction unit that is configured to predict the power generation amount of the power plant by using the selected mathematical model, wherein the similar track record data extraction unit is configured to extract the weather track record similar to the weather prediction data, to extract an output power track record at a time of the weather track record stored at an output power track record database, and thereby obtain the weather track record and the output power track record in combination, in order to calculate the power generation amount with high accuracy even when an amount of the track record data of the generator power generation amount is insufficient or an amount of weather track record data similar to a weather prediction result is small, characterized in that the model generation unit is configured to obtain the mathematical model by adding a characteristic and an installation condition of the power plant to a primary mathematical model of the power plant generated based on the weather track record and the output power track record.