A curved secondary battery includes an electrode assembly; a first sealing sheet at a first surface of the electrode assembly; a second sealing sheet at a second surface of the electrode assembly, the first sealing sheet and the second sealing sheet together sealing the electrode assembly; and a reinforcing layer on the first sealing sheet, wherein the first sealing sheet has a concavely curved surface, and wherein the reinforcing layer has a curvature corresponding to a curvature of the first sealing sheet.