A cap assembly and a secondary battery having the same which can prevent current from flowing out of the battery by preventing contact of a broken vent member with a cap. The vent member is broken due to an internal pressure of the secondary battery greater than a predetermined level. The cap assembly includes a vent member having a plurality of notches formed in a radial direction from the center of the vent member and a plurality of reinforcement parts formed between the notches. The cap assembly may include a vent member having a plurality of notches formed between two adjacent notches so that the vent member folds when the internal pressure of the secondary battery is too great.