SCREW CUTTING CONTROLLER

PROBLEM TO BE SOLVED: To improve screw cutting accuracy or the like when drilling and screw cutting are continuously executed in a workpiece by a single compound tool provided with a screw cutting part continued to a drilling part in a tip end side. SOLUTION: By selecting from a function generator of a principal control circuit B in a screw cutting control device, a first function formed by a first pitch relating to drilling action and a second function formed by a second pitch relating to screw cutting action time, and setting a spindle rotational speed, a compound tool 15 is moved toward a workpiece 17 at a feed speed respectively synchronized with an arithmetic result, screw cutting work is executed to be continued to drilling work.