To provide a repairing method for a cutter capable of preventing falling of an edge part.

This is a method to provide a new edge part 16' by forming a rectangular recessed part 17 by machining on an old edge part which is an abrased part of a knife edge part 14, preheating this knife edge part 14 in a temperature range of 350-400°C, postheating it for about an hour in a temperature range of 350-400°C after applying build-up welding 18 on the recessed part 17 of the knife edge part 14 and removing an excess thickness part 18a of the build-up welding 18 by polishing.