Provided is an air conditioner. The air conditioner includes a water tank to store water, a visual body disposed over the water tank and formed of a transparent material, a watering housing to draw water stored in the water tank and to spray the drawn water to the visual body, a water level sensor to measure a water level of the water tank in a multi-stage, a top cover assembly disposed over the visual body and having a water supply hole to supply water to the water tank, and a water level display unit disposed beside the water supply hole of the top cover assembly to display a water level measured by the water level sensor in a multi-stage.