To provide a new cutter blade holder excellent in portability and allowing a user to conduct the chamfering work easily.

A first slit insertable with a thin plate-like cutter blade into a plate-like body having a flat face section from the surface of the plate-like body to the back face nearly in parallel with the surface is formed. A second slit allowing the thin plate-like cutter blade to be protruded nearly in parallel with the surface of the plate-like body is formed at the prescribed interval from the first slit, and a wall section on which the tip section of the exposed cutter blade abuts is formed at the prescribed interval from the second slit. The wall section has a nearly V-shaped abutment edge on a plane, and a magnetic substance is stuck between the first slit and the second slit along the cutter blade inserted between both slits.