A curved secondary battery including an electrode assembly having a curved shape, and a pouch sealing the electrode assembly. The pouch includes a first sealing sheet on a first surface of the electrode assembly, a second sealing sheet on a second surface of the electrode assembly, the first sealing sheet and the second sealing sheet sealing the electrode assembly, and a wing portion formed on a side of the electrode assembly by bound-together edges of the first sealing sheet and the second sealing sheet. The wing portion includes a body portion bent in a first direction and a reinforcement portion that is continuous with the body portion and is bent in a second direction to overlap the body portion. The second direction may be opposite to the first direction.