[Object] To provide a ball end mill in which it is possible to improve wear resistance in the vicinity of the central axis at the tip of a ball-nosed end cutting edge and to suppress vibration of a tool body during machining.[Solution] A ball end mill 10 includes: a tool body 1 that rotates about a central axis O; and an arc-shaped ball-nosed end cutting edge 2 in a side view which is provided to start from the central axis O side on a tip side of the tool body 1 toward a rear side thereof. The ball-nosed end cutting edge 2 has a radius of curvature r that becomes gradually smaller from the central axis O side toward a periphery Q side.