PURPOSE: To improve the operating efficiency of a machine tool and a tool feeding device by providing a means of making a tool feeding schedule according to machining and machining order data and a means of changing said schedule in a control unit, and changing said schedule in accordance with change in the machining operation of said machine tool.

CONSTITUTION: Machining and machining order data are inputted from an upper control unit 5 into a control unit 3, a tool feeding schedule which is controlled by a tool housing part 21, a tool assembling/disassembling part 22, and a tool conveying part 23, is prepared and sent to a feed control part 24, and a machine tool 11 starts machining via a numerical control part 12. The control unit 3 monitors change in machining operation and changes the tool feeding schedule in accordance with changes such as an indication of change in machining contents, extension or reduction in machining time, etc. and sends it to the feed control part 24, to reduce the waiting time for the machine tool 11. Also, in case of stopping machining operation due to a trouble, the tool feeding schedule is changed and sent to the feed control part 24 to reduce the waiting time.