A laundry treating apparatus comprising: a cabinet; a laundry receiving space provided in the cabinet to provide a space for receiving laundry therein; a support assembly provided in the laundry receiving space configured to support the laundry; a first chamber in communication with the laundry receiving space through a discharging opening and a supplying opening and positioned below the laundry receiving space; an insertion opening provided in a front face of the cabinet in communication with the laundry receiving space; a communication opening provided in the front face of the cabinet in communication with the first chamber; a duct provided in the first chamber to connect the discharging opening and the supplying opening with each other; a first heat exchanger provided inside the duct configured to dehumidify air entered into the duct; a second heat exchanger provided inside the duct configured to heat air passed through the first heat exchanger; a chamber door configured to open and close the communication opening, wherein the chamber door is a drawer withdrawable from the first chamber and insertable to the first chamber, and configured to reciprocate between a first point where the chamber door closes the communication opening and a second point where the chamber door opens the communication opening for exposing the water discharge tank out of the first chamber; a water discharge tank detachably connected to the chamber door and configured to store condensate water discharged from the first heat exchanger therein; characterized in that: a control command input unit configured to generate an extension command for moving the chamber door from the first point to the second point in respond to a user's request and an insertion command for moving the chamber door from the second point to the first point in respond to the user's request, and a chamber door conveying part configured to allow the chamber door to reciprocate between the first point and the second point in response to the extension command and the insertion command. a cabinet; a laundry receiving space provided in the cabinet to provide a space for receiving laundry therein; a support assembly provided in the laundry receiving space configured to support the laundry; a first chamber in communication with the laundry receiving space through a discharging opening and a supplying opening and positioned below the laundry receiving space; an insertion opening provided in a front face of the cabinet in communication with the laundry receiving space; a communication opening provided in the front face of the cabinet in communication with the first chamber; a duct provided in the first chamber to connect the discharging opening and the supplying opening with each other; a first heat exchanger provided inside the duct configured to dehumidify air entered into the duct; a second heat exchanger provided inside the duct configured to heat air passed through the first heat exchanger; a chamber door configured to open and close the communication opening, wherein the chamber door is a drawer withdrawable from the first chamber and insertable to the first chamber, and configured to reciprocate between a first point where the chamber door closes the communication opening and a second point where the chamber door opens the communication opening for exposing the water discharge tank out of the first chamber; a water discharge tank detachably connected to the chamber door and configured to store condensate water discharged from the first heat exchanger therein; characterized in that: a control command input unit configured to generate an extension command for moving the chamber door from the first point to the second point in respond to a user's request and an insertion command for moving the chamber door from the second point to the first point in respond to the user's request, and a chamber door conveying part configured to allow the chamber door to reciprocate between the first point and the second point in response to the extension command and the insertion command. a control command input unit configured to generate an extension command for moving the chamber door from the first point to the second point in respond to a user's request and an insertion command for moving the chamber door from the second point to the first point in respond to the user's request, and a chamber door conveying part configured to allow the chamber door to reciprocate between the first point and the second point in response to the extension command and the insertion command.