Abstract: A card lock structure for selectively locking or releasing a lock barrel includes a card lock casing and a card barrel limiting mechanism. The card lock casing has a card-inserting groove. The card barrel limiting mechanism has a lock barrel limiting push rod pivotally disposed in the card lock casing, an elastic element disposed between the card lock casing and the lock barrel limiting push rod, and a movable pressing unit for pressing the lock barrel limiting push rod. One end of the lock barrel limiting push rod projects outside the card lock casing in order to selectively lock or release the lock barrel. When a card passes through the card-inserting groove to push the movable pressing unit to release the lock barrel limiting push rod, the lock barrel limited push is moved by the elasticity of the elastic element in order to release the lock barrel.