A method for controlling a clothes treatment apparatus , the clothes treatment apparatus comprising: a tub configured to accommodate water; a drum rotatably arranged in the tub and configured to accommodate clothes; a communication tube operatively connected with a water level in the tub such that a pressure formed in the communication tube varies depending on the water level in the tub ; a chamber provided at a free end of the communication tube and communicating with the communication tube such that a pressure formed in the chamber corresponds to a water level of the tub ; an elastic part provided in the chamber and arranged to be elastically deformed according to a change in pressure of the chamber ; an output unit configured to generate an electrical signal (X i ) corresponding to an amount of deformation of the elastic part , the output unit comprising a plurality of gage resistors arranged on one surface of the elastic part ; and a controller configured to receive the electrical signal (X i ) and sense the water level in the tub by comparing the electrical signal (X i ) with a reference electrical signal (X o ) indicating a zero water level of the tub , the method comprising: draining water contained within the tub ; detecting the electrical signal (X i ) of the output unit; comparing the detected electrical signal (X i ) with the reference electrical signal (X 0 ); and correcting the reference electrical signal (X 0 ) when a difference between the reference electrical signal (X 0 ) and the detected electrical signal (X i ) is outside a predetermined first set range, wherein the correcting corrects the reference electrical signal (X 0 ) by a preset magnitude. a tub configured to accommodate water; a drum rotatably arranged in the tub and configured to accommodate clothes; a communication tube operatively connected with a water level in the tub such that a pressure formed in the communication tube varies depending on the water level in the tub ; a chamber provided at a free end of the communication tube and communicating with the communication tube such that a pressure formed in the chamber corresponds to a water level of the tub ; an elastic part provided in the chamber and arranged to be elastically deformed according to a change in pressure of the chamber ; an output unit configured to generate an electrical signal (X i ) corresponding to an amount of deformation of the elastic part , the output unit comprising a plurality of gage resistors arranged on one surface of the elastic part ; and a controller configured to receive the electrical signal (X i ) and sense the water level in the tub by comparing the electrical signal (X i ) with a reference electrical signal (X o ) indicating a zero water level of the tub , the method comprising: draining water contained within the tub ; detecting the electrical signal (X i ) of the output unit; comparing the detected electrical signal (X i ) with the reference electrical signal (X 0 ); and correcting the reference electrical signal (X 0 ) when a difference between the reference electrical signal (X 0 ) and the detected electrical signal (X i ) is outside a predetermined first set range, wherein the correcting corrects the reference electrical signal (X 0 ) by a preset magnitude. draining water contained within the tub ; detecting the electrical signal (X i ) of the output unit; comparing the detected electrical signal (X i ) with the reference electrical signal (X 0 ); and correcting the reference electrical signal (X 0 ) when a difference between the reference electrical signal (X 0 ) and the detected electrical signal (X i ) is outside a predetermined first set range, wherein the correcting corrects the reference electrical signal (X 0 ) by a preset magnitude. <EOS>