METHOD OF PROCESSING DEEP HOLE

PROBLEM TO BE SOLVED: To provide a method of processing a deep hole, using drills dispensing with a removal process of burrs generated on a through-hole in the outside and the inside of a workpiece.SOLUTION: The method of processing the deep hole includes: for the workpiece member 10 in which a processing start surface 11 and a processing completion surface 12 are inclined surfaces or curved surfaces, a first process of processing the processing start surface 11 using the first drill having a point angle of 180°; and a second process od processing the deep hole at a first feed speed using the second drill having a total length longer than the first drill and a point angle of 180° after the first process. Further, a third process may be added for penetrating the processed hole to the processing completion surface 12 at a second feed speed slower than the first feed speed after the second process. Furthermore, a value of the second feed speed in the third process divided by the diameter of the second drill may be in a range of 0.005-0.06.