In the machine tool (10) pertaining to the present invention, an imaging device (33) takes an image of a tool (20) being moved in the feeding direction. Contour lines (51) are identified by means of the plurality of sets of image data generated from imaging. The movement trajectory (52) and the central axis (53) of the tool (20) are identified on the basis of the contour lines (51). When the movement trajectory (52) and the central axis (53) are offset, said offset can be used to correct the positioning of the tool (20) with the machine tool (10). As a result, the processing accuracy of a workpiece improves. Moreover, when the dimensions of a tool (20) that has a tilted posture are measured, it is possible to determine the actual tool diameter or the actual blade position in the tilted posture. The aforementioned blade position and tool diameter can be used to correct the positioning of the machine tool (10). Thus, the processing accuracy of the workpiece improves even more.