BATTERY CASE AND SECONDARY BATTERY INCLUDING THE SAME

Provided is a technique to prevent formation of a gap between a case body and a sealing plate. The battery case (41) disclosed herein includes: a case body (41a) having an opening (41a1); and a substantially rectangular sealing plate (41b) attached to the opening (41a1). The sealing plate (41b) has a pair of long side portions (91, 92), a pair of short side portions (93, 94), and R portions (95 - 98) at four corners. An edge of a lower surface (41b2) of the sealing plate (41b) is chamfered. A chamfering amount of the short side portions (93, 94) is greater than a chamfering amount of the long side portions (91, 92). Each the R portions (95 - 98) comprises a gradual change region (962), where a chamfering amount gradually decreases from a first end (P1) on a side of the short side portions (93, 94) toward a second end (P2) on a side of the long side portions (91, 92).