Boring control method

A boring control method for a machine tool for automatically boring a deep hole using a central control means performing boring with programmed control. In the boring, the number of processing and steps of the machine tool is kept minimum, load torque of a tool is detected continuously using torque detection means, and the movement of the tip portion of the tool desired for a piece of work is confirmed from a reference point to a hole bottom using a Z-axis movement device. The boring is continued in each step until the load torque exceeds a predetermined torque limit value, performed in a condition where a main shaft rotation number, or rotation speed of the tool, and feed speed form a specific pattern, and a condition is set where a total step number (f) does not exceed a predetermined limit step number (N).