PURPOSE: To obtain a machining method that its machining accuracy is excellent and its automatizing can be easily made by progressively feeding a longitudinal member by a pre-scheduled amount corresponding to its machining part and machining each machining part.

CONSTITUTION: A longitudinal member 10 is provided with at least more than one are machining parts. At least one of machining units 2a to 2e is arranged on a feed direction line corresponding to respective machining parts, is and the part is machined. One end side 17 of the longitudinal member 10 is made a head, a pre-scheduled feeding amount is progressively fed corresponding to the machining part from the scheduled standard point 7, and each machining part is machined with each machining unit 2a to 2e. The longitudinal member 10 is, for example, a window frame member. In such a way, machining can be flexibly corresponded against many kinds of machining shapes, dimensions of the longitudinal member.