Embodiments of the present invention provides a pouch film. In manufacturing a secondary battery, a gas may be generated when reacting an electrode assembly with an electrolyte. After the generated gas is discharged, the pouch film may be sealed. In this case, a deformation part may be formed in the gas chamber section which serves as a passage for discharging the gas, specifically, in the gas chamber passage, thus to prevent the electrolyte from flowing backward and maintain shapes of the gas chamber inlet during injecting the electrolyte.