A pouch case sealing apparatus for sealing a pouch case that includes a pouch body for accommodating an electrode assembly of a battery cell and a pouch terrace extending from the pouch body is provided. The pouch case sealing apparatus includes: a pair of sealing jigs, each sealing jig having a pressing surface, the pair of sealing jigs being configured to press and thermally fuse the pouch terrace from upper and lower directions of the pouch terrace so that the pouch case is sealed; and a pair of terrace anti-protruding units formed at respective pressing surfaces of the pair of sealing jigs to prevent an end portion of the pouch terrace from protruding beyond the pouch body in a horizontal direction of the pouch body when the pouch terrace is pressed and thermally fused. A method for sealing a pouch case is also provided.