A front-loading washing machine comprising: a housing comprising a door to be opened and closed on a front; a washing tub provided to be spinnable inside the housing , shaped like a cylinder opened toward the front facing the door , and comprising one or more locking holes on a lateral side; and one or more lifters provided inside the washing tub , coupled to the washing tub through the locking holes , and lifting up laundry based on spinning of the washing tub , the lifter comprising a locking member passing through the locking hole , bent at an outside of the washing tub and extended in a spinning axis direction of the washing tub , and the locking hole comprising a first edge to which the locking member is locked to couple the lifter and the washing tub , and a second edge and a third edge adjacent to opposite ends of the first edge and surrounding the locking member to face with each other, wherein the lifter comprises a fastening boss protruding from a bottom of the lifter , and the washing tub comprises a fastening hole to be fastened with the fastening boss by a screw, characterized in that the locking member comprises: an erect portion erectly extended from a bottom of the lifter and provided to be in contact with the first edge , an end portion bent from the erect portion , perpendicular to the erect portion , and extending in the spinning axis direction, and an inclined portion provided between the erect portion and the end portion , and inclined at a predetermined angle to an axis line of the spinning axis direction. a housing comprising a door to be opened and closed on a front; a washing tub provided to be spinnable inside the housing , shaped like a cylinder opened toward the front facing the door , and comprising one or more locking holes on a lateral side; and one or more lifters provided inside the washing tub , coupled to the washing tub through the locking holes , and lifting up laundry based on spinning of the washing tub , the lifter comprising a locking member passing through the locking hole , bent at an outside of the washing tub and extended in a spinning axis direction of the washing tub , and the locking hole comprising a first edge to which the locking member is locked to couple the lifter and the washing tub , and a second edge and a third edge adjacent to opposite ends of the first edge and surrounding the locking member to face with each other, wherein the lifter comprises a fastening boss protruding from a bottom of the lifter , and the washing tub comprises a fastening hole to be fastened with the fastening boss by a screw, characterized in that the locking member comprises: an erect portion erectly extended from a bottom of the lifter and provided to be in contact with the first edge , an end portion bent from the erect portion , perpendicular to the erect portion , and extending in the spinning axis direction, and an inclined portion provided between the erect portion and the end portion , and inclined at a predetermined angle to an axis line of the spinning axis direction. an erect portion erectly extended from a bottom of the lifter and provided to be in contact with the first edge , an end portion bent from the erect portion , perpendicular to the erect portion , and extending in the spinning axis direction, and an inclined portion provided between the erect portion and the end portion , and inclined at a predetermined angle to an axis line of the spinning axis direction. <EOS>