To simply and inexpensively manufacture the highly efficient relief type diffraction optical element by including the cutting process to form a relief pattern using a cutting tool, whose cutting edge has a prescribed curved shape, during the production of the element.

A relief type diffraction lens is manufactured by cutting a free-cutting optical substrate material 1 such as plastic using a recessed type curvature cutting tool 2. The tool 2 is provided with a recessed type curvature cutting tool chip 3 on its tip part. The chip 3 has a recessed type curvature cutting edge 4 with a prescribed curve. The shape of the curve is obtained by averaging the curves introduced from the portion having a widest pitch of the relief type diffraction lens to be manufactured and the phase shift function of the portions having second and third wide pitches. Then, the tool 2 and the material 1 are mounted on a precision lathe, the material 1 is rotated and the tool 2 is moved in parallel with the rotation of the material 1 to conduct the cutting process.