To provide a reamer tool having improved machinability for reducing the surface roughness of a machined surface.

The reamer tool comprises a first machining part 11, and a second machining part 12. The first machining part 11 has such a tapered shape that its diameter is smaller as tending to the axial front end side, and it has a plurality of abrasive grains 13 fixed onto the surface. The second machining part 12 is provided on the axial base end side of the fist machining part 11, and it has a plurality of abrasive grains 14 fixed onto the surface with their diameters smaller than the abrasive grains 13 of the first machining part 11.