A regenerating method of a cutting blade to be repaired includes a chamfering step of chamfering a leading edge part and side edge parts of a cutting blade, a build-up welding step of welding a build-up on the chamfered leading edge part and the chamfered side edge parts, and a processing step of regenerating and processing build-up welding portions of the cutting blade into a specified shape of the leading edge part and the side edge parts, and of the build-up welding portions formed on the side edge parts, such that a dimension L1 of a lateral build-up weld zone is 1 to 3 times a dimension L2 of an outer build-up weld zone.