A control device for an industrial machine comprising a numerical control device (10) and a programmable controller (130), the numerical control device (10) comprising: a data processing section essentially comprising a memory (1) and a central processing unit (2), for analyzing and operating input numerical data, outputs of the data processing section being used for performing numerical control of a machine to be controlled and of rotation of a spindle (31) of the machine; a gear ratio data memory (12a) for storing gear ratio data of gears through which a spindle motor (27) is coupled to a spindle head (31) holding a tool (16), the gear ratio data being applied to the gear ratio data memory (12a) through a bus from the programmable controller (130) adapted to perform sequence control of the machine; and synchronous operation controller (2, 3) for calculating actual speed of rotation of the tool through operation using the gear ratio data and a feedback signal of the spindle motor (27), and performing synchronous operation control of the tool (16) and a feed shaft (21).