A secondary battery and a method of manufacturing the same are disclosed. In one embodiment, the secondary battery includes an electrode assembly including an external surface, an electrolyte, a sealing tape including an adhesive layer attached to at least portion of an outer surface of the electrode assembly and contacting the external surface of the electrode assembly and a base sheet disposed on an adhesive layer and formed of a material having directionality, and a can receiving the electrode assembly, the electrolyte, and the sealing tape, wherein the base sheet loses directionality and is shrunk and deformed in shape by contact with the electrolyte, and at least portion of the base sheet contacts an inner surface of the can to prevent the electrode assembly from being freely moved within the can.