PURPOSE: To efficiently perform a more exact, more precise and more beautiful cutting working as well as to obtain a more excellent resistance to wear by attaching a hard grinding grain to the surface of a blade and an outer diameter blade of a cutting edge part.

CONSTITUTION: This boring reamer consists of a guide part 2 adjoining the handle part 1 and a blade part 3 which is formed from the guide part to the point. This blade part 3 is formed by a cemented cobide with an excellent resistance to wear and a plurality of edges 4 are installed thereto. A left twisting angle of approximately 50W70° is formed to this edge 4 and a starting taper angle 5 of approximately 20° or less at the front part is formed and at the rear part, an outer diameter edge 6 is formed to promote a banishing. Further, a clearance angle 7 of approximately 5° or less is formed at an edge having the angle 5 and the shape of a groove 8 is made into a saw edge type. And a hard grinding grain 10 such as CBN or a diamond grinding grain is attached to the edge 4 of the blade part 3 and the edge 6 by means of an electroplating method. With this, a precise and beautiful cutting working can be efficiently performed and an excellent resistance to wear is obtained.