PURPOSE: To feed a tool automatically to each machine tool receiving a workpiece by an automatically conveyed pallet without laying a machining line all over so as to improve space efficiency by providing the pallet with a tool holding means.

CONSTITUTION: Numerous NC machine tools 2 controlled by control devices 21 connected to a main controller 1 are provided in a row. The pallet conveyor device 3 is provided with conveyor trucks 32 traveling on a carrier path 31 provided along the lined-up direction of the NC machine tools 2 so as to convey pallets 4. The pallet 4 for placing a workpiece W is additionally provided with a tool holder 5 for holding a tool T for machining the workpiece W. The correction value of the tool T stocked in a tool stocker 51 is measured by a correction value measuring device 52, and the measured correction value is transferred to the control device 21 through the main controller 1. As a result, a tool conveyor means and data control for correspondence between the correction value and the tool T are respectively dispensed with.