PURPOSE: To enable simple and rapid binding of plurality of pieces of paper sheet and thereby prevent the pieces from becoming scattered and lost by providing blades which project sheetlike parts and also providing receiving holes into which the blades and the sheetlike parts formed on the paper sheets are introduced on the other side.

CONSTITUTION: Blades 12 on an upper blade seat 10 are fitted downward into receiving holes 22 on a lower blade seat 20 together with the sheet-like parts of paper sheets P while being cut and therefore, the sheetlike parts project toward the lower blade seat 20, that is, in the cutting direction, to be formed into projecting parts P0 facing downward. In addition, the blades 21 on the lower blade seat 20 are fitted into receiving holes 11 on the upper blade seat 10. For this reason, projecting parts P1 facing downward are formed on the paper sheets P. Next, a rocking arm 1 is made to break away from a base seat 2 to extract the paper sheets P from a space between both blade seats 10, 20. Thus numerous projection parts P0. P1 formed on the paper sheets P themselves penetrate the other paper sheets P as claws so that a plurality of pieces of the paper sheet P are bounded together.