PURPOSE: To shorten extremely the length between a first blade for roughing and a second blade for finishing, provide a long regrinding length, minimize processing residual, improve chamferring performance of the first blade, and improve accuracy of finishing face.

CONSTITUTION: A reamer is provided with two lines of first chip discharge grooves 11, a second chip discharge groove 12 in the outer circumference of the land between them, and a sub-land having an outside diameter smaller than that of the land between the first and the second chip discharge grooves 11, 12. A second blade 17 for finishing which is located on the base end side of a first blade 15 is provided in the second chip discharge groove 12. And the outer circumferencial part of the sub-land is formed into an eccentric relief 19 which is gradually closer to the internal circumferencial side as it approaches from the tip edge rearward and a radial step difference between the first blade 15 and the second blade 17 is set to 0.02-0.5mm.