This endmill is provided with: an endmill body which is shaft-shaped and is rotatable about an axial line and which is provided with, at a leading end thereof, a plurality of gashes which extend radially and are arranged along the circumferential direction; and a plurality of cutting edges which are provided to the leading-end side ridges of wall surfaces, of the gashes, directed in the endmill rotational direction. The rotation trajectory of the cutting edges is a circular-arc shape projecting toward the leading-end side, in which the circular-arc center is located on the axial line in a side view. The curvature radius of the rotation trajectory of the cutting edges is larger than 1/2 of the outer diameter of the endmill body. The tips of the cutting edges are bent so as to project toward the rotational direction, in a planar view. The size of the maximum projection of the tips of the cutting edges toward the rotational direction with respect to a virtual line connecting both radial ends of the tips is 3-4% of the outer diameter of the endmill body. The cutting edges include master and slave edges.
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