of the staple gun main body 15 the staple gun main body 15 has a cylinder block 24 and a cylinder head 23 a coupler 26 is arranged below the handle 21 of the staple gun 20 the coupler 26 is connected to a coupler not depicted of a compressed air supply hose not depicted compressed air supplied from the coupler 26 is introduced to the cylinder head 23 through the interior of the handle 21 when the trigger 22 is pulled thus the compressed air is supplied to the cylinder block 24 the cylinder block 24 has a built in piston not depicted a staple driver is fixed to this piston the staple driver extends from the cylinder block 24 to the staple injection nozzle and moves reciprocally in a staple injection path 43 fig1 fig4 to fig6 in the staple injection nozzle 25 in accordance with the reciprocal movement of the piston inside the staple injection path 43 a staple inlet 43 a fig4 to fig6 is formed for supplying u shaped staples one by one from the staple guide 27 fig7 the staple injection nozzle 25 has a nozzle body 28 attached to the staple gun main body 15 and a cover plate 29 attached to the upper portion of the nozzle body 28 on the nozzle body 28 a staple injection path 43 is formed the cover plate 29 defines the upper portion of the staple.