An air conditioner is provided that may include a case in which a heat exchanger is disposed and having an air inlet and an air outlet; a discharge pipe that communicates with the air outlet and extends outside of the case; and a kit having a discharge port in which the discharge pipe is fixed, and configured to be disposed at a window frame. The kit may include a main board in which the discharge port is formed; at least one sub-board configured to be movable up and down with respect to the main board; a rack connected with one of the main board or the at least one sub-board and forming a plurality of grooves spaced apart from each other in an upward-downward direction; and a holder connected with the other one of the main board or the at least one sub-board and having a protrusion inserted into one of the plurality of grooves to restrict upward-downward movement of the at least one sub-board.