Endmill body and radius end mill

An end mill body made of ceramic and constituting being a distal-end side of a radius end mill to be rotated about an axial line, having

• a chip ejection groove formed in a periphery of a distal end portion of the end mill body as to extend from a distal-end side toward a rear-end side while twisting in a direction opposite a direction of rotation,
• a peripheral cutting edge formed on a peripheral-side ridge of the chip ejection groove,
• a gash extending from a distal end portion of the end mill body to the chip ejection groove,
• an end cutting edge rake face formed on the gash,
• an end cutting edge formed on the distal end portion of the end mill body,
• a corner R cutting edge arcuately extending from the end cutting edge to the peripheral cutting edge as to be outwardly convex, and
• a corner R rake face provided between the end cutting edge rake face and the chip ejection groove as to adjoin the corner R cutting edge,
• with a point A representing an intersection of the corner R cutting edge and the end cutting edge and with a point B representing an intersection of the corner R cutting edge and the peripheral cutting edge, as viewed from a direction perpendicular to a plane which contains the axial line and passes through the point B,
• wherein a point C represents an intersection of a straight line A in parallel with the axial line and passing through the point A and a straight line B perpendicular to the axial line and passing through the point B and that when a region surrounded by the straight line A, the straight line B, and the corner R cutting edge is divided by a straight line C passing through the point C and through a midpoint of a straight line extending from the point A to the point B, a region A represents a region located on a side toward the point A with respect to the dividing straight line C, and a region B represents a region located on a side toward the point B with respect to the dividing straight line C,
• the corner R rake face not existing in the region A, and being formed as to contain the point B and to exist in at least the region B.