Disclosed is an air conditioner with an enhance efficiency. The air conditioner An air conditioner includes: an indoor part for inhaling indoor air to exchange heat with an indoor heat exchanger, and again discharging the heat-exchanged air into an indoor space; an outdoor part for inhaling an outdoor air to exchange heat with an outdoor heat exchanger, and again discharging the heat-exchanged air into an outdoor space; a base partitioned into the outdoor part and the indoor part and loaded on the partitioned outdoor part and indoor part; and a cabinet provided to cover both sides and a rear surface of the outdoor part, and having an insertion guide formed at a lower portion thereof.