to guide projection 320 a first group of teeth 330 is located in a first portion m of the top surface of buckler body 310 while a second group of teeth 330 is located in a second portion n of the top surface of buckler body 310 as shown in fig5 threshold side 332 of first portion m has an angle a with a first plane perpendicular to a second plane of the surface of the buckler body 310 while threshold side 332 of second portion n has an angle u03b2 with the first plane perpendicular to the second plane of the surface of the buckler body 310 angle a of threshold side 332 of teeth 330 formed in first portion m is greater than angle u03b2 of threshold side 332 of teeth 330 formed in second interval n when a sheet is jumped up while passing through guide projection 320 and when remaining sheets slide along guide projection 320 and are located in first portion m and second portion n of teeth 330 due to vibration respective ends of the sheets are remained between thresholds side 332 and sliding side 334 of teeth 330 the sheets remained between thresholds side 332 and sliding side 334 of teeth 330 is picked up one by one and separated by threshold side 332 of teeth 330 hook 340 is extended downwardly from a side of buckler body 310 and has an outwardly.