PURPOSE: To project and retract an edge at one touch by forming a horizontal hole on a steel plate and installing the edge into the horizontal hole by a screw and assembling the steel plate having a lever and a stopper inside a cutter knife cover.

CONSTITUTION: A horizontal hole 3 for adjusting the projection degree of an edge 2 is formed on a steel plate 1. The edge 2 is installed into the horizontal hole 3 by a screw 4, and the steel plate 1 and the edge 2 are integrally formed. A lever 5 and a stopper 6 for stopping the lever at a certain position are installed at the top edge of the steel plate 1. The cutter, lever, and the steel plate having the stopper are assembled inside a cutter knife cover 7. When a small article such as a string and paper is cut by using a cutter knife, the edge 2 is projected and retracted by sliding the lever 5. Since a lever for projecting and retracting the edge 2 is installed at the top edge of the cutter knife, the edge 2 can be projected and retracted at one touch without changing the hands for taking the cutter knife.