The turning machine according to the present invention includes a displacement sensor (200) which measures a distance between an immobile reference point and a position of variable point which reflects the positional displacement of the tool, the immobile reference point being able to determine a relative positional correlation relating to a variable position of tools with the progress of machining of the workpiece (W) by the tool (421). In drawings the reference point is set up in the guide bush (90). And based on the measured result by the displacement sensor, the tool is moved so that the center height of the tool and the center line of the workpiece satisfy relatively the predetermined positional correlation. Accordingly, the center height deviation amount due to heat deformation and the like is corrected.