The present disclosure relates to a method for controlling a laundry treating apparatus including a cabinet having a laundry inlet defined therein, a tub providing a space to store water and including a tub inlet defined therein, a connection body connecting the laundry inlet with the tub inlet, a drum rotatably disposed inside the tub to store laundry therein, an air supply including a chamber located above the tub, a chamber supply flow channel guiding air inside the tub to the chamber, and a tub supply flow channel guiding air in the chamber to the connection body, a heat exchanger assembly that sequentially performs dehumidification and heating of air introduced into the chamber, and a detergent supply that supplies detergent to the tub via a detergent supply pipe, wherein the detergent supply opens and closes the detergent supply pipe.