A method of controlling a generation quantity of a wind power plant, comprising: a) monitoring a generation state of the wind power plant comprising a plurality of wind power generators, wherein said monitoring the generation state of the wind power plant comprises: a1) receiving current weather information about an area where the wind power plant is placed and previous weather information; and a2) monitoring a generation quantity of the wind power plant by periods based on the received weather information; b) analyzing (ST200; 3) a generation quantity reduction factor of a wind power generator that has a reduced generation quantity and that belongs to the plurality of wind power generators if the generation quantity of the wind power generator is reduced to a smaller generation quantity than that in a normal state; and c) individually controlling the generation quantity of the wind power generator having the reduced generation quantity based on the analyzed reduction factor so that the generation quantity is increased; wherein b1) said analyzing the generation quantity reduction factor step comprises checking (ST202; 20) whether or not contaminants have been attached to a blade of the wind power generator by partitioning the wind power plant into a plurality of zones and comparing attachment degrees of the contaminants in the partitioned zones with each other; and further comprising: b2) checking, if it is determined that contaminants have not been attached to the blade, whether or not a rotational velocity of the blade has been reduced, whether or not vibration has been generated in the blade, and whether or not a weight of the blade has been increased; and b3) checking weather conditions around the wind power plant again. a) monitoring a generation state of the wind power plant comprising a plurality of wind power generators, wherein said monitoring the generation state of the wind power plant comprises: a1) receiving current weather information about an area where the wind power plant is placed and previous weather information; and a2) monitoring a generation quantity of the wind power plant by periods based on the received weather information; a1) receiving current weather information about an area where the wind power plant is placed and previous weather information; and a2) monitoring a generation quantity of the wind power plant by periods based on the received weather information; b) analyzing (ST200; 3) a generation quantity reduction factor of a wind power generator that has a reduced generation quantity and that belongs to the plurality of wind power generators if the generation quantity of the wind power generator is reduced to a smaller generation quantity than that in a normal state; and c) individually controlling the generation quantity of the wind power generator having the reduced generation quantity based on the analyzed reduction factor so that the generation quantity is increased; wherein b1) said analyzing the generation quantity reduction factor step comprises checking (ST202; 20) whether or not contaminants have been attached to a blade of the wind power generator by partitioning the wind power plant into a plurality of zones and comparing attachment degrees of the contaminants in the partitioned zones with each other; and further comprising: b2) checking, if it is determined that contaminants have not been attached to the blade, whether or not a rotational velocity of the blade has been reduced, whether or not vibration has been generated in the blade, and whether or not a weight of the blade has been increased; and b3) checking weather conditions around the wind power plant again. b1) said analyzing the generation quantity reduction factor step comprises checking (ST202; 20) whether or not contaminants have been attached to a blade of the wind power generator by partitioning the wind power plant into a plurality of zones and comparing attachment degrees of the contaminants in the partitioned zones with each other; and further comprising: b2) checking, if it is determined that contaminants have not been attached to the blade, whether or not a rotational velocity of the blade has been reduced, whether or not vibration has been generated in the blade, and whether or not a weight of the blade has been increased; and b3) checking weather conditions around the wind power plant again.