The present disclosure discloses an apparatus and method for sealing a pouch case that optimizes a sealing shape or structure of a sealing portion at an inner side of the pouch case to ensure insulation of a secondary battery. The apparatus for sealing a pouch case of a pouch-type secondary battery according to the present disclosure includes an upper compression jig to apply pressure to a sealing portion of the pouch case in a downward direction, and a lower compression jig to apply pressure to the sealing portion of the pouch case in an upward direction, and at least one of the upper compression jig and the lower compression jig applies the pressure to the pouch case at different depths at an inner side end and an outer side end.