Rotation tool having function of fixing workpiece

A machine tool for machining a workpiece having a cross-sectional shape in which an outer shape becomes gradually smaller along an axial direction, the machine tool comprising:

• a rotation tool mounted to a spindle through a tool holder;
• and a workpiece support member fixed to a table;
• wherein the rotation tool includes a cutter holding portion which is fixed to the tool holder and to which blade portion is fixed;
• a fixing device which fixes the workpiece to the workpiece support member by pressing the workpiece, the workpiece support member includes a hole that is formed so as to match the outer shape of the workpiece and in which the workpiece is disposed, the blade portion is disposed at a tip end of the cutter holding portion on a side toward the workpiece, the fixing device includes a movement portion formed to be movable translationally along an axis parallel with the spindle in the interior of the cutter holding portion, a pressing device which presses the movement portion to a side toward the workpiece, a shaft portion rotatably supported relative to the movement portion and disposed coaxially with the spindle, and a pressing portion which is disposed at a tip end of the shaft portion and presses an inner surface of the workpiece, the pressing portion is formed in a plate shape so as to correspond to a shape of a portion of the workpiece with which the pressing portion comes into contact, and the workpiece is fixed to the workpiece support member solely by the pressing portion of the fixing device and when the pressing portion presses the workpiece toward the workpiece supporting member so that the fixing device fixes the workpiece to the workpiece supporting member.