Ball end mill

Provided is a ball end mill that is able to perform both cutting processing and polishing processing satisfactorily and allows cutting resistance at a tip thereof to be small. In this ball end mill, in the outer circumference of a tool body 1, a plurality of chip discharge grooves 2 are formed from the tip of a tool toward the base end side of the tool, and ball blades 5, 6 are provided to a crossing ridgeline portion between rake surfaces 3 of the chip discharge grooves 2 and a tip spherical surface 4 of the tool body 1. In the ball end mill, a tool rotation center O is present on the tip spherical surface 4, and the ball blade 5 is provided such that a distance X, from the tool rotation center O, to the closest point to the tool rotation center O for the one ball blade 5 when viewed from the tip of the tool, is set so as to be shorter than the same distance Y for the other ball blade 6.