Variable lead end mill

A variable lead end mill having a plurality of peripheral cutting edges with different helix angles,

• the variable lead end mill having a flute bottom diameter of a plurality of helix flutes making up rake faces of the plurality of the peripheral cutting edges, the flute bottom diameter d increasing in an axial direction from a tool tip toward a shank.

The variable lead end mill of claim 3, wherein

• the variable lead end mill has a plurality of end cutting edges continuously from the plurality of the peripheral cutting edges, wherein the end cutting edges are disposed with gashes at gash angles having different degrees depending on the helix angle, and wherein the gash angles are made larger when the helix angle is larger as compared to when the helix angle is smallest.