Abstract: An end mill includes a body having a core receiving recess and a cutting insert releasably mounted thereon. An upper surface of the insert has a first cutting edge ridge serving as an outer peripheral cutting edge, a second cutting edge ridge providing an end cutting edge and a third cutting edge ridge providing an inner peripheral cutting edge. The upper surface has a corner where the second and third cutting edge ridge intersecting each other. The upper surface is composed of a central portion and a corner portion including the corner, whereby the third cutting edge ridge comprising a first edge portion defined by a ridge of the corner portion and a second edge portion defined by a ridge of the central portion. At least that portion of the corner portion disposed adjacent the central portion is inclined providing a thickness of the insert is progressively reduced toward the corner. The insert has a negative radial rake at the outer peripheral cutting edge and a positive axial rake.