Abstract: An exemplary break mechanism is sued for a nail gun having a security slide rod, a magazine, a hitting slot configured for containing a signal nail, a nail guiding track disposed between the hitting slot and the magazine, the nail guiding track being capable of guiding a plurality of chain of nails into the hitting shot one by one, a side cover configured for covering the nail guiding track. The break mechanism includes an elastic member disposed between the break member and the side cover, the elastic member is configured to drive the break member to swing towards the hitting slot and the nail guiding track; and a break member having a detection portion and a block member. The detection portion is capable of detecting push action of a single nail in the hitting slot and the nail in the nail guiding track adjacent to the nail in the hitting slot. When the break member is pushed by the nail in the hitting slot or the adjacent nail in the nail guiding track, the block member releases the security slide rod.