To provide a shearing system for L-shaped steel member which is operated easily and very light.

An L-shaped steel member 2 is clamped by a fixed cutter 35 and a movable cutter 30, so that a shearing system can be positioned and be ready for shearing. So far both cutters 30, 35 are verl light, the system operation is very easy and simple. Projecting a piston rod 23 causing the movable cutter to advance so that the L shaped steel member 2 can be at the right position, and the unnecessary structures can be eliminated. Movable cutter 30 is positioned at a distance from a structure 1 so that the deformation taken place at the unnecessary portion can be removed, thereby, the sheared face remained at the structure 1 is left clean and not deformed condition.