Secondary Battery and Battery Pack Including the Same

According to one aspect of the present invention, the secondary battery includes: a waterproof part configured to surround at least a portion of a circumference of the electrode assembly so that a gas within the exterior passes through the waterproof part, but a liquid within the exterior does not pass through the waterproof part; and a vent part provided in an inner surface of the exterior to provide a path through which the gas within the exterior is discharged to the outside when an internal pressure of the exterior exceeds a certain value.