A method of controlling an air conditioner includes a step of sensing the capacitance of condensed water through a plurality of electrode pads to sense the level of condensed water stored in a condensed water storage part during cooling, a step of sensing an increase in the level of condensed water and calculating an amount of condensed water that is generated per unit time based on the sensed increase in the level of condensed water, a step of comparing the sensed level of the condensed water with a drainage level stored in a memory, and a step of operating a drainage pump based on the sensed level of condensed water or the calculated amount of condensed water that is generated per unit time.