An output control device for a wind farm provided with a plurality of wind power generation devices, the control device comprising: a potential estimation unit configured to estimate a maximum amount of electrical power which can be output by each wind power generation device per a certain control cycle for the wind farm; a control amount determination unit configured to determine, based on an available power generation amount of each wind power generation device, a control amount on an effective power of each wind power generation device in the wind farm; wherein said control amount determination unit comprises a control amount distribution unit configured to calculate the available power generation amount by subtracting an effective power detected value and a predefined spinning reserve of the wind farm from the maximum amount of electrical power estimated by the potential estimation, and to determine a distribution gain to distribute the control amount to each wind power generation device based on the available power generation amount: the control amount distribution unit comprises a distribution gain determination unit configured to increase the distribution gain of the wind power generation device with a larger available power generation amount such that a total of the distribution gains is equal to a total number (n) of the wind power generation devices to determine the control amount per the control cycle, the distribution gain determination unit is configured such that, per the control cycle, it: divides the spinning reserve by the number n of the wind power generation devices to calculate each spinning reserve of the wind power generation devices, calculates an average gain that is an average of an integral of a gain of each wind power generation device, subtracts the average gain from the available power generation amount of each wind power generation device, integrates the subtracted value to obtain an integral value, and generates the distribution gain of each wind power generation device based on the integral value. a potential estimation unit configured to estimate a maximum amount of electrical power which can be output by each wind power generation device per a certain control cycle for the wind farm; a control amount determination unit configured to determine, based on an available power generation amount of each wind power generation device, a control amount on an effective power of each wind power generation device in the wind farm; wherein said control amount determination unit comprises a control amount distribution unit configured to calculate the available power generation amount by subtracting an effective power detected value and a predefined spinning reserve of the wind farm from the maximum amount of electrical power estimated by the potential estimation, and to determine a distribution gain to distribute the control amount to each wind power generation device based on the available power generation amount: the control amount distribution unit comprises a distribution gain determination unit configured to increase the distribution gain of the wind power generation device with a larger available power generation amount such that a total of the distribution gains is equal to a total number (n) of the wind power generation devices to determine the control amount per the control cycle, the distribution gain determination unit is configured such that, per the control cycle, it: the control amount distribution unit comprises a distribution gain determination unit configured to increase the distribution gain of the wind power generation device with a larger available power generation amount such that a total of the distribution gains is equal to a total number (n) of the wind power generation devices to determine the control amount per the control cycle, the distribution gain determination unit is configured such that, per the control cycle, it: divides the spinning reserve by the number n of the wind power generation devices to calculate each spinning reserve of the wind power generation devices, calculates an average gain that is an average of an integral of a gain of each wind power generation device, subtracts the average gain from the available power generation amount of each wind power generation device, integrates the subtracted value to obtain an integral value, and generates the distribution gain of each wind power generation device based on the integral value.