Cutting tool

A cutting tool that rotates about a rotation axis, the cutting tool comprising:

• a tip end portion, wherein
• the tip end portion includes a partially spherical surface that is brought into contact with a workpiece,
• the partially spherical surface is provided with a plurality of concave indentations recessed into the partially spherical surface, defining a plurality of recesses, each recess having a bottom surface and being disposed apart from each other, and
• a sharp opening edge of each of the plurality of recesses defined at an intersection between an upper most portion of the recess and the partially spherical surface constitutes a cutting edge,
• wherein the opening edge of each of the plurality of recesses has in plan view an equivalent circle diameter having a closed shape, the equivalent circle diameter being greater than or equal to 1 μm and less than or equal to 100 μm, wherein the equivalent circle diameter of each of the recesses is a square root of a value obtained by dividing an area of the recess in plan view by πT/4;
• and
• the tip end portion is formed of binderless cubic boron nitride or nano polycrystalline diamond.