A control system for plural numerically controlled machine tools comprising a main conveyor and a buffer conveyor for transferring a plurality of work pallets accorded with coded numbers. The buffer conveyor has a plurality of buffer areas. A plurality of machining modules classified by machining processes are arranged in association with buffer areas of the buffer conveyor. A plurality of rails arranged above the machining modules extend transversely of the main and buffer conveyors with a pallet transfer device suspended by each rail for selectively transferring the work pallets into its associated buffer area and main conveyor and for selectively transferring the work pallets from the associated buffer area into the associated machining module in response to the coded numbers on the work pallets. At least one of the machining modules includes not less than two numerically controlled machine tools performing the same function arranged along the rail. A central control device is provided for transmitting information to each numerically controlled machine tool in accordance with the coded number of the work pallet transferred in the machine tool.