An air conditioner is disclosed. Herein, the air conditioner can maintain the ambient air of a specific space (or area) to a pleasant state by adequately adjusting the temperature, humidity, and air current distribution within the corresponding space to allow people to pleasantly carry out their everyday activities. Since unwanted insects can be repelled or eliminated by using ultrasonic waves that do not contaminate the indoor air, the air conditioner can protect the human body from unwanted insects or pests while maintaining the air within the indoor space to a clean state. Also, carbon dioxide and specific light rays preferred by mosquitoes are used to attract unwanted insects into the main body, thereby eliminating the attracted insects by using ultrasonic waves. Thus, unwanted insects and, more particularly, mosquitoes existing in the room that is to be air-conditioned may be quickly eliminated.