A pressing jig for removing gas generated in an activation process of a battery cell includes a plate-shaped lower plate on which the battery cell that has undergone the activation process is placed and fixed, and an upper plate that presses the battery cell placed on the lower plate from above. At least one of the upper plate or the lower plate has a structure in which n (n≥3) separated sub-plates are assembled to form a single plate, and the sub-plates independently press the battery cell. The pressing jig can suppress trapping of internal gas by sequentially pressing the battery cell.