Abstract: A locking mechanism for a nail gun includes a side slot formed on a bottom side of a gun body and a nail supplying slot connected to a drive track of the nail gun. A stopper element is formed on a side of a slider element corresponding to the side slot. The gun also includes a magazine in which a nail pusher facing the nail supplying slot and a lockout element facing the side slot are formed. The nail pusher has an ear portion. The lockout element includes a pushing arm and a moveable guide slot capping with the ear portion to restrict the sliding movement of the lockout element on the nail pusher. As the pushing arm extends towards the corresponding end of the nail supplying slot, a nail is pushed into the drive track to shoot. The lockout element enters into the side slot to block the stopper element when the nail is exhausted, so as to enhance the shooting blocking effect of the nail gun.