A hand-operated stapler comprises an arm, a sliding belt and a blocking member, wherein the arm comprises a front end which acts as an effort, a rear end which acts as a fulcrum, and a load portion in between the front end and the rear end of the arm; and the rear end of the blocking member is connected to a front end of the sliding belt. At a non-stapling default position a front end of the blocking member is biased to be disposed above the stopper and blocks the upper clincher member from engaging with the lower clincher member. At a stapling position the rear end of the sliding belt is pulled upward, thereby pulling the blocking member rearward and away from the stopper and thus allowing the upper clincher member to engage with the lower clincher member.