Abstract: An MPU storage device 114 stores a device address of an image display device 11, and an MPU identification processing device 113 acquires and retains the device address stored in the MPU storage device 114. The MPU identification processing device 113 acquires the device address from a device information storage device 122 or an MPU identification processing device 123 according to a DDC communication protocol, using an output side data sending and receiving device 115. The device information storage device 122 stores EDID, and the MPU identification processing device 113 acquires EDID stored in the device information storage device 112, compares it with the EDID acquired from the image display device 12, extracts common data, and stores it in the device information storage device 112 as common EDID data of the image display device 11 and the image display device 12.