A method for manufacturing an electrode assembly, the method comprising: a preparation step of preparing a plurality of electrode stacks in which an electrode and a separator are alternately stacked; a stacking step of stacking the plurality of electrode stacks on each other; a packaging step of wrapping and packaging a circumferential portion of the plurality of stacked electrode stacks using a separator member; and a fixing step of heating and pressing the separator member to fix the plurality of stacked electrode stacks, and characterized in that, in the preparation step, folded electrode stacks are prepared, in the fixing step, the separator member wound around the circumferential portion of the electrode stacks is heated and pressed by a hot press, and the separator member wraps a body portion except both ends of the electrode stacks in a direction parallel to a direction in which an electrode lead coupled to the electrode stacks protrudes, and wherein, when the separator member that wraps the electrode stacks is spread, the separator member comprises a first area, a second area, and a third area, which are sequentially arranged and have a width that corresponds to a width of the electrode stack, and a fourth area, which is arranged continuously from the third area and has a width less than the width of the electrode stacks, and the electrode stacks are attached to the first area and the third area, wherein, when the fourth area wraps the electrode stack, at least a portion of the fourth area wraps the electrode stack to overlap the other area of the separator member, and when the overlapping portion between the fourth area and the other area of the separator member is heated and pressed by the hot press, the separator member is fused to each other to allow the plurality of electrode stacks to be fixed by the separator member in the state in which the electrode stacks are stacked. a preparation step of preparing a plurality of electrode stacks in which an electrode and a separator are alternately stacked; a stacking step of stacking the plurality of electrode stacks on each other; a packaging step of wrapping and packaging a circumferential portion of the plurality of stacked electrode stacks using a separator member; and a fixing step of heating and pressing the separator member to fix the plurality of stacked electrode stacks, and characterized in that, in the preparation step, folded electrode stacks are prepared, in the fixing step, the separator member wound around the circumferential portion of the electrode stacks is heated and pressed by a hot press, and the separator member wraps a body portion except both ends of the electrode stacks in a direction parallel to a direction in which an electrode lead coupled to the electrode stacks protrudes, and wherein, when the separator member that wraps the electrode stacks is spread, the separator member comprises a first area, a second area, and a third area, which are sequentially arranged and have a width that corresponds to a width of the electrode stack, and a fourth area, which is arranged continuously from the third area and has a width less than the width of the electrode stacks, and the electrode stacks are attached to the first area and the third area, wherein, when the fourth area wraps the electrode stack, at least a portion of the fourth area wraps the electrode stack to overlap the other area of the separator member, and when the overlapping portion between the fourth area and the other area of the separator member is heated and pressed by the hot press, the separator member is fused to each other to allow the plurality of electrode stacks to be fixed by the separator member in the state in which the electrode stacks are stacked.