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 acrossing 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). 本发明提供一种球头立铣刀，其能够良好地进行切削加工以及研磨加工这双方，而且末端部的切削阻力小。一种球头立铣刀，在刀具主体(1)的外周形成有从工具末端朝向基端侧的多个切屑排出槽(2)，