End mill

An end mill comprising a tool body having a shaft-like shape, said tool body having a cutting edge portion formed on one end thereof, said cutting edge portion having an end cutting edge formed at a front end of said one end of said tool body, said cutting edge portion forming a rotary circle of a rotary locus thereof and having a plurality of circumferential cutting edges formed on the circumference thereof along a longitudinal axis of said tool body, a cross-section perpendicular to the longitudinal axis of the cutting edge portion being of constant shape along the longitudinal axis,

• said cutting edge portion having the circumferential surface thereof comprising concave surfaces receding inwardly toward the longitudinal axis of said tool body and convex surfaces projecting outwardly radially of said cutting edge portion, each of said concave surfaces and each of said convex surfaces being alternately arranged with each other circumferentially on a cross section perpendicular to said axis of said tool body, each of said convex surfaces having one end thereof meeting the rotary circle of said rotary locus on said cross section perpendicular to said axis of said tool body, said rotary locus formed by said circumferential cutting edges, said each of said convex surfaces having a curvature gradually growing larger from said one end toward the other end of said convex surface, each of said convex surfaces receding toward a centerline of said cutting edge portion, whereby said one end of each of said convex surfaces intersecting one adjacent concave surface of said concave surfaces forms said circumferential cutting edge, each of said concave surfaces forming a rake face, each of said convex surfaces forming a flank.