An air conditioner is disclosed. The air conditioner includes a suction chamber provided with an indoor suction port, through which indoor air is suctioned, an outdoor suction port, through which outdoor air is suctioned, the suction chamber being configured to selectively adjust a ratio of outdoor air to be suctioned to indoor air to be suctioned, an outdoor discharge chamber disposed at one side of the suction chamber, the outdoor discharge chamber being provided with an outdoor discharge port, through which air in the suction chamber is discharged outdoors, and an indoor discharge chamber disposed at the other side of the suction chamber, the indoor discharge chamber being provided with an indoor discharge port, through which air in the suction chamber is discharged indoors. When discharging indoor air, it is possible to adjust a proportion of outdoor air introduced indoors.