A front-loading washing machine comprising: a housing (110, 210) comprising a door (140, 211) to be opened and closed on a front; a washing tub (120, 220, 300, 600, 710, 810, 910, 1000) provided to be spinnable inside the housing (110, 210), shaped like a cylinder opened toward the front facing the door (140, 211), and comprising one or more locking holes (621, 711, 811, 911, 1011) on a lateral side; and one or more lifters (130, 230, 340, 400, 500) provided inside the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), coupled to the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) through the locking holes (621, 711, 811, 911, 1011), and lifting up laundry based on spinning of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), the lifter (130, 230, 340, 400, 500) comprising a locking member (440, 520, 720, 820, 920) passing through the locking hole (621, 711, 811, 911, 1011), bent at an outside of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) and extended in a spinning axis direction of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), and the locking hole (621, 711, 811, 911, 1011) comprising a first edge to which the locking member (440, 520, 720, 820, 920) is locked to couple the lifter (130, 230, 340, 400, 500) and the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), and a second edge and a third edge adjacent to opposite ends of the first edge and surrounding the locking member (440, 520, 720, 820, 920) to face with each other, wherein the lifter (130, 230, 340, 400, 500) comprises a fastening boss protruding from a bottom of the lifter (130, 230, 340, 400, 500), and the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) comprises a fastening hole to be fastened with the fastening boss by a screw, characterized in that the locking member (440, 520, 720, 820, 920) comprises: an erect portion erectly extended from a bottom of the lifter (130, 230, 340, 400, 500) 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 (110, 210) comprising a door (140, 211) to be opened and closed on a front; a washing tub (120, 220, 300, 600, 710, 810, 910, 1000) provided to be spinnable inside the housing (110, 210), shaped like a cylinder opened toward the front facing the door (140, 211), and comprising one or more locking holes (621, 711, 811, 911, 1011) on a lateral side; and one or more lifters (130, 230, 340, 400, 500) provided inside the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), coupled to the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) through the locking holes (621, 711, 811, 911, 1011), and lifting up laundry based on spinning of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), the lifter (130, 230, 340, 400, 500) comprising a locking member (440, 520, 720, 820, 920) passing through the locking hole (621, 711, 811, 911, 1011), bent at an outside of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) and extended in a spinning axis direction of the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), and the locking hole (621, 711, 811, 911, 1011) comprising a first edge to which the locking member (440, 520, 720, 820, 920) is locked to couple the lifter (130, 230, 340, 400, 500) and the washing tub (120, 220, 300, 600, 710, 810, 910, 1000), and a second edge and a third edge adjacent to opposite ends of the first edge and surrounding the locking member (440, 520, 720, 820, 920) to face with each other, wherein the lifter (130, 230, 340, 400, 500) comprises a fastening boss protruding from a bottom of the lifter (130, 230, 340, 400, 500), and the washing tub (120, 220, 300, 600, 710, 810, 910, 1000) comprises a fastening hole to be fastened with the fastening boss by a screw, characterized in that the locking member (440, 520, 720, 820, 920) comprises: an erect portion erectly extended from a bottom of the lifter (130, 230, 340, 400, 500) 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 (130, 230, 340, 400, 500) 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.