An end mill is disclosed which includes a tool body having a shaft-like shape. The tool body has a cutting edge portion formed at one end thereof. The cutting edge portion has a plurality of circumferential cutting edges formed on the circumference thereof along the longitudinal axis of the tool body. The end mill is characterized in that the cutting edge portion has the circumferential surface thereof which includes rake faces and flanks. Each of the rake faces adjoins one of two adjacent circumferential cutting edges. Each of the flanks intersects with one of the rake faces at one end and adjoins the other of the two adjacent circumferential cutting edges at the other end. The rake faces have a rake angle arranged between a range of 5 DEG to -45 DEG at a cross section perpendicular to the axis of the tool body. The flanks have a relief angle arranged between a range of 20 DEG to 45 DEG at a cross section perpendicular to the axis of the tool body. In one embodiment, the circumferential surface of the cutting edge portion is formed of an alternately connected plurality of concave surfaces receding inwardly toward the center of the cutting edge portion, with different ranges of rake and relief angles.
