When the system is powered on, a BOOT device detecting unit detects which data exchange device (memory card or the like) is to be booted first, and the detected data exchange device is booted first. A data exchange process program which is set as software starting at BOOT is started to detect a data exchange file. At this time, with reference to a type code of a numerical control apparatus to be used, data matched to the type code is selected. A data exchange file is transferred to an internal storing device to which the data exchange device is connected. Then, a data exchange file is transferred to an internal storing device to which the data exchange device is not connected.