A peripheral device which is adapted to perform designated processing based on information coming from an information processing device, the peripheral device comprising: an image reading unit; a communication unit which is adapted to communicate with the information processing device; a storage unit (127, 203) which stores a control program, which is loadable to a RAM of the information processing device via said communication unit and executable by the information processing device to control the peripheral device, and stores a control file for controlling the peripheral device; and a control unit which is adapted to control operation of said image reading unit based on a control command written into the control file stored in said storage unit by the information processing device which executes the control program loaded to the RAM of the information processing device, wherein said storage unit includes: a ROM which stores the control program and is not recognizable from the information processing device, and a RAM which stores the control file and is recognizable from the information processing device, and wherein said control unit is further adapted to: copy the control program from the ROM to the RAM, control the operation of the peripheral device based on the control command written into the control file by the information processing device, and write image data obtained by said image reading unit into the control file readable by the information processing device, wherein the peripheral device is recognized as a readable and writeable storage area by the information processing device, and whereby the information processing device is enabled to monitor whether the image data is written into the control file and to read out the image data from the control file upon the image data being written into the control file. an image reading unit; a communication unit which is adapted to communicate with the information processing device; a storage unit (127, 203) which stores a control program, which is loadable to a RAM of the information processing device via said communication unit and executable by the information processing device to control the peripheral device, and stores a control file for controlling the peripheral device; and a control unit which is adapted to control operation of said image reading unit based on a control command written into the control file stored in said storage unit by the information processing device which executes the control program loaded to the RAM of the information processing device, wherein said storage unit includes: a ROM which stores the control program and is not recognizable from the information processing device, and a RAM which stores the control file and is recognizable from the information processing device, and wherein said control unit is further adapted to: copy the control program from the ROM to the RAM, control the operation of the peripheral device based on the control command written into the control file by the information processing device, and write image data obtained by said image reading unit into the control file readable by the information processing device, wherein the peripheral device is recognized as a readable and writeable storage area by the information processing device, and whereby the information processing device is enabled to monitor whether the image data is written into the control file and to read out the image data from the control file upon the image data being written into the control file. copy the control program from the ROM to the RAM, control the operation of the peripheral device based on the control command written into the control file by the information processing device, and write image data obtained by said image reading unit into the control file readable by the information processing device, wherein the peripheral device is recognized as a readable and writeable storage area by the information processing device, and whereby the information processing device is enabled to monitor whether the image data is written into the control file and to read out the image data from the control file upon the image data being written into the control file.