To easily set first projecting amount of a distal end part of a cutting tool to required projecting amount to be adjusted or projecting amount approximate to the amount, in a cutting device.

This tool for adjusting the projecting amount of the distal end part of the cutting tool has a substrate 21 having a flat surface, a cutting tool holder part 22 for holding the cutting tool to an almost vertical attitude in relation to the substrate 21 by making the distal end part abut on the surface of the substrate 21, and spacer plates 23a to 23e having thickness corresponding to the projecting amount of the distal end part to be adjusted of the cutting tool or the approximate thickness and held between the surface of the substrate 21 and a workpiece abutting part of a machining head.