A multi-unit air conditioner and a method for controlling the same are disclosed which are capable of preventing continuous introduction of a refrigerant into indoor units in an OFF state where the indoor units can be independently powered on or off, thereby preventing a degradation in the cooling and heating efficiencies. The air conditioner includes a plurality of indoor units each including a power controller adapted to independently power on or off an associated one of the indoor units, an outdoor unit connected with the indoor units, the outdoor unit including a microcomputer for controlling an operation of the outdoor unit, and enabling the outdoor unit to communicate with the indoor units, and a controller for determining whether each of the indoor units is in a normal operation state or in a non-operation state, and controlling an operation of a distributor in accordance with the result of the determination.