To achieve supporting a rigid body of a blade support in a support frame, and achieve the optimum support position of the blade support and minimum bending moment introduced to the support frame through the blade support in cutting.

This cutter of a sheet material, especially for a stack of sheets, is provided with the support frame 1, a blade forcedly guided and simultaneously moved vertically in sideways motion, two rectilinear guide parts disposed obliquely at various angles for the blade support 7 storing the blade and supported by rolling, and a driving means for moving the blade support 7. The respective rectilinear guide parts have at least one guide rail 23 connected to the support frame 1 and a forcedly guided guide reciprocating bed 26.