Disclosed are an air conditioner and a control method therefor. The air conditioner includes: a main body; a filter configured to filter impurities externally introduced into the main body; a fan configured to introduce the impurities into the main body through the filter; a sensor configured to detect a filter state value for determining a state of the filter; and a processor configured to determine that a replacement time of the filter arrives when an impurity purification capacity calculated on the basis of the filter state value detected in real time by the sensor is lower than a reference value.