A method for manufacturing an electrode assembly, the method comprising: a preparation step of preparing a separator and an electrode ; an electrode unit manufacturing step of manufacturing an electrode unit having a structure in which the separator and the electrode are alternately disposed; a pre-sealing step of forming a pre-sealing part in which at least partial regions of the plurality of separators within the electrode unit are attached to each other; and a separator cutting step of cutting a region of the plurality of separators , which comprises the pre-sealing part, characterized in that , in the preparation step, a concave part is formed in the electrode, and a recess part having a recessed shape that is curved toward the electrode is formed in the concave part , the pre-sealing part is formed on at least a portion of the plurality of separators , which covers the concave part of the electrode , upper and lower portions of the electrode unit are pressed by each of an upper pressing device and a lower pressing device at the same time to form the pre-sealing part , each of an upper pressing device and a lower pressing device has a bar shape, one end of each of the upper pressing device and the lower pressing device presses a region of the separator , which is adjacent to the concave part of the electrode , and a curved surface having a curvature corresponding to that of the recess part is formed in one end of each of the upper pressing device and the lower pressing device which press a region of the separator , which is adjacent to the concave part of the electrode , and in the separator cutting step, a concave part and a recess part are formed in the separator , which corresponds to the concave part and the recess part of the electrode . a preparation step of preparing a separator and an electrode ; an electrode unit manufacturing step of manufacturing an electrode unit having a structure in which the separator and the electrode are alternately disposed; a pre-sealing step of forming a pre-sealing part in which at least partial regions of the plurality of separators within the electrode unit are attached to each other; and a separator cutting step of cutting a region of the plurality of separators , which comprises the pre-sealing part, characterized in that , in the preparation step, a concave part is formed in the electrode, and a recess part having a recessed shape that is curved toward the electrode is formed in the concave part , the pre-sealing part is formed on at least a portion of the plurality of separators , which covers the concave part of the electrode , upper and lower portions of the electrode unit are pressed by each of an upper pressing device and a lower pressing device at the same time to form the pre-sealing part , each of an upper pressing device and a lower pressing device has a bar shape, one end of each of the upper pressing device and the lower pressing device presses a region of the separator , which is adjacent to the concave part of the electrode , and a curved surface having a curvature corresponding to that of the recess part is formed in one end of each of the upper pressing device and the lower pressing device which press a region of the separator , which is adjacent to the concave part of the electrode , and in the separator cutting step, a concave part and a recess part are formed in the separator , which corresponds to the concave part and the recess part of the electrode . <EOS>