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 (97A, 97B, 97C, 97D) 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 (97A, 97B, 97C, 97D) 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.