A ceiling mounted air conditioner is provided. The ceiling mounted air conditioner includes a main body configured to be fixed onto a ceiling and have an open bottom; an outlet panel configured to be coupled to a lower part of the main body and have a plurality of air outlets; an intake panel configured to be coupled to the outlet panel and have an air intake; a door panel configured to be lifted up or down from the bottom of the intake panel and thus to open or shut the air intake; and a human body sensor module configured to be installed in the door panel, to begin to operate when the door panel is lifted down and to sense a movement of a user. Since the ceiling mounted air conditioner can blow air-conditioned air toward the user in a localized manner, it is possible to improve the performance of the ceiling mounted air conditioner.