Abstract: Provided is a taper reamer with which it is possible to achieve an improvement in machining accuracy and machining life. The taper reamer comprises a plurality of cutting edges each having a helical shape provided on the outer periphery of a cutting-edge portion having an external diameter being expanded from a front end toward a rear end thereof, wherein an intertooth angle, defined between each of a pair of the cutting edges adjacently arranged in a circumferential direction, is different from one another at any given reference position, and wherein the plurality of cutting edges each have a helix angle that is different from one another. As the plurality of cutting edges that are unequally partitioned each have the helix angle that is different from one another, a resonance during cutting can be prevented.