at the surface of the base part 20 whereby the contract area of blank paper s becomes smaller and consequently the feeding load becomes smaller the driving pulley 7 which is fitted to the driving shaft 2 and turns integrally with the latter is rotatably supported by driving shaft 7 within a hole 25 of the frame proper 10 and a hole 26 of the guide frame 11 the guide shaft 3 is rotatably and slidably received through holes 27 and 28 of frames 10 and 11 respectively and a lock means 40 the presser member 13 has a slit 30 made at the position corresponding to the moving path of the belt 6 carrying pins and also axis parts 31 32 33 34 which engage with engaging holes 14a 15a of the support parts 14 15 or 16 17 of the frame proper 10 axis parts 31 32 33 34 are projected from arm parts 36 37 38 39 in the same direction arm parts 36 39 at the outer side are longer than the arm parts 37 38 at the inner side and top parts as pawl parts 36a 39a engage elastically with concaves 14b 15b and hold the presser member 13 at the specified opened degree the axis parts 31 33 and the axis parts 32 24 project in opposite direction respectively the lock means 40 which fixes the pin tractor 1 to the guide shaft 3 has a tubular fixing member 41 fitted to the guide shaft 3 provided at the frame proper 9 and a lever member 42 fitted movably to said.