A device for manufacturing an electrode assembly by winding a separator sheet around a plurality of unit cells arranged on the separator sheet, the device comprising: a conveyor configured to introduce the separator sheet on which the plurality of unit cells are arranged toward a winder and a cutter; the cutter located apart from the conveyor and configured to cut a part of the separator sheet spaced a predetermined distance apart from a first unit cell in a running direction while the first unit cell located at a head in the running direction of the separator sheet among the plurality of unit cells is located on the winder; a lower air blowing unit located below the cutter and configured to spray air onto an end part of the separator sheet so that the end part of the cut separator sheet is able to be bent in an upward direction from the ground; the winder located between the conveyor and the cutter and configured to sequentially laminate the plurality of unit cells by a method of firstly winding the first unit cell in a counterclockwise direction with a top surface of the first unit cell facing the ground, and repeatedly secondarily winding the first unit cell after waiting for a predetermined time to operate while the end part of the separator sheet is bent; and an upper air blowing unit configured to spray air onto the end part of the separator sheet so that the end part of the separator sheet is able to be bent in a downward direction toward the ground of the first unit cell while the first unit cell is firstly wound, the upper air blowing unit spraying air downward onto the separator sheet for 0.10 to 0.35 seconds with a spray pressure of 0.1 to 0.5Mpa, and the lower air blowing unit spraying air onto the separator sheet at an air pressure of 0.2 to 0.5MPa. a conveyor configured to introduce the separator sheet on which the plurality of unit cells are arranged toward a winder and a cutter; the cutter located apart from the conveyor and configured to cut a part of the separator sheet spaced a predetermined distance apart from a first unit cell in a running direction while the first unit cell located at a head in the running direction of the separator sheet among the plurality of unit cells is located on the winder; a lower air blowing unit located below the cutter and configured to spray air onto an end part of the separator sheet so that the end part of the cut separator sheet is able to be bent in an upward direction from the ground; the winder located between the conveyor and the cutter and configured to sequentially laminate the plurality of unit cells by a method of firstly winding the first unit cell in a counterclockwise direction with a top surface of the first unit cell facing the ground, and repeatedly secondarily winding the first unit cell after waiting for a predetermined time to operate while the end part of the separator sheet is bent; and an upper air blowing unit configured to spray air onto the end part of the separator sheet so that the end part of the separator sheet is able to be bent in a downward direction toward the ground of the first unit cell while the first unit cell is firstly wound, the upper air blowing unit spraying air downward onto the separator sheet for 0.10 to 0.35 seconds with a spray pressure of 0.1 to 0.5Mpa, and the lower air blowing unit spraying air onto the separator sheet at an air pressure of 0.2 to 0.5MPa.