To provide a taper honing processing technology for allowing cutting expansion/contraction movement to be highly accurately interlocked with a reciprocal movement of a honing grindstone with a predetermined relationship and making a load applied to the honing grindstone uniform as much as possible.

A servo motor for reciprocally driving a spindle and a servo motor for cutting driving are used as a spindle reciprocal driving source for reciprocally moving a rotary spindle 2 having a honing tool 1 in the axis direction of a tapered inner diameter surface Wa of a workpiece W and a cutting driving source for allowing the honing grindstone 10 to carry out cutting expansion movement, respectively. The cutting expansion movement of the honing grindstone 10 is synchronized with and conformed to the reciprocal movement of the honing tool 1. Therefore the movements of both the servo motors are interlocked with each other, and a tapered grindstone surface 10a of the honing grindstone 10 is moved in parallel with the tapered inner diameter surface Wa of the workpiece W by the lifting/lowering stroke movement of the honing tool 1.