A stapler configured to bind a workpiece (P) using a non-metal staple , the staple having a crown portion and a pair of leg portions extending from respective ends of the crown portion , the stapler comprising: an operating member supported rotatably; a penetrating part including a pair of cutting blades spaced apart from each other, wherein the penetrating part is configured to form holes in the workpiece (P) and to cause the leg portions of the staple to penetrate the workpiece (P) by rotation of the operating member and inserting and withdrawing the cutting blades with respect to the workpiece (P); wherein the operating member is operable to cause the leg portions of the staple to penetrate the workpiece (P) by the penetrating part ; and a bending part configured to bend the leg portions of the staple , which has penetrated the workpiece (P) by the penetrating part , along the workpiece to bond the leg portions to each other, wherein the operating member is configured such that a distance between a force receiving portion and a fulcrum axis of rotation and a distance between a force acting portion and the fulcrum axis changes by shifting the fulcrum axis in accordance with the operation of the operating member , so as to change a reduction rate of a load applied to the operating member , wherein the operating member includes a cam groove which is configured to allow movement of the fulcrum axis, wherein the cam groove is guided along a shaft installed to a body section , wherein the distance between the force receiving portion and the fulcrum axis of rotation and the distance between the force acting point and the fulcrum axis are displaced by a shape of the cam groove . an operating member supported rotatably; a penetrating part including a pair of cutting blades spaced apart from each other, wherein the penetrating part is configured to form holes in the workpiece (P) and to cause the leg portions of the staple to penetrate the workpiece (P) by rotation of the operating member and inserting and withdrawing the cutting blades with respect to the workpiece (P); wherein the operating member is operable to cause the leg portions of the staple to penetrate the workpiece (P) by the penetrating part ; and a bending part configured to bend the leg portions of the staple , which has penetrated the workpiece (P) by the penetrating part , along the workpiece to bond the leg portions to each other, wherein the operating member is configured such that a distance between a force receiving portion and a fulcrum axis of rotation and a distance between a force acting portion and the fulcrum axis changes by shifting the fulcrum axis in accordance with the operation of the operating member , so as to change a reduction rate of a load applied to the operating member , wherein the operating member includes a cam groove which is configured to allow movement of the fulcrum axis, wherein the cam groove is guided along a shaft installed to a body section , wherein the distance between the force receiving portion and the fulcrum axis of rotation and the distance between the force acting point and the fulcrum axis are displaced by a shape of the cam groove . <EOS>