To enable anyone to obtain a uniform and highly accurate chamfered state.

A blade B is used by being mounted on the tip end of a grip handle 10 directly or through a blade holder H. The blade B includes: a straight mounting shaft part 20 having a circular cross section; an inclined shaft part 22 that is extended bent with an obtuse angle once in an eccentric direction from the tip end of the mounting shaft part; and an eccentric shaft part that bends with an obtuse angle further in the opposite direction from the tip end of the inclined shaft part. A cutting blade 23 machined on the ventral side of a region transiting from the inclined shaft part to the eccentric shaft part faces in the direction where a longitudinal center line exists in the mounting shaft part, in the hand-operated chamfering tool T. A blade advancing guide hump 25 composed of a material softer than a workpiece W is fixedly integrated to the tip end of the eccentric shaft part in the blade, in an overall covered state or a partially humped state. Then, a circular arcuate face part 25a, which protrudes from the tip end of the eccentric shaft part to at least the existing direction of the longitudinal center line in the mounting shaft part, comes in line contact with the surface of the workpiece during the hand-operation, thereby stabilizing advancing operation of the cutting blade.