To improve machining pitch accuracy by using a multi-stripe machining tool.

(a) A first machining or creating notch 4' of a workpiece 1 is inserted with a first spiral blade 5' of a machining tool 2 to make the workpiece 1 engaged with the machining tool 2, and then the workpiece 1 is machined by the machining tool 2 in the engaged state, (b) the machining tool 2 and the workpiece 1 are disengaged, and (c) the first spiral blade 5' of the machining tool 2 is inserted from the first machining notch 4' of the workpiece 1 to a second different notch 4'' to make the workpiece 1 engaged with the machining tool 2 again and the workpiece 1 is machined by the machining tool 2.