To solve the problem of a conventional system that it is difficult to mass-produce seam rippers, which can cut well stably, because a prior art is one by which anyone can do work since there is the necessity to perform processing while thinking of the shape and diameter of a grinder, the number of revolutions, the angle of arrangement, power, etc., when processing a cutting edge, so it needs a skill.

The cutting edge is nipped and fixed with the tips of the body of a seam ripper made vertically symmetrically to be bent from the center. The cutting edge is a razor blade. A hole is bored in the cutting edge. The method consists of the forming process for forming the body of the seam ripper made vertically symmetrically into roughly V form so as to bend it from the center, the insertion process for inserting the cutting edge into the tip end, and a pressure welding process for nipping and fixing the cutting edge.