In a ball end mill, cutting can be carried out with high precision, and abrasion or breakage of the cutting blade can be reduced. The ball end mill is provided with a cutting blade section having a cutting blade, which is U-shaped in front view, at the end section of a shank. The cutting blade is provided on a flat surface deviated by a predetermined distance from the shank axis, and comprises blade faces having rake faces, which become negative angles at the time of cutting. In cross-section intersecting the cutting blade, all the blade faces have the same shape.