A laundry treatment apparatus has a cabinet, a laundry receiving space in the cabinet, and a predetermined space for accommodating laundry. A laundry introduction opening in communication with the laundry receiving space is provided in a front surface of the cabinet. A supply unit supplies air or vapor to the laundry receiving space. A laundry support unit is movably coupled to the cabinet. A door is rotatably coupled to the cabinet and opens and closes the laundry introduction opening. A window is provided in the door and is made of a transparent material. The laundry treatment apparatus also has a knock sensing unit that senses a sound or vibration generated when a user knocks on the window. Additionally, the laundry treatment apparatus has a lamp that emits light in the laundry receiving space when the knock sensing unit senses the sound or vibration generated when the window is knocked.