A display device comprising: an external input interface connected to a source device; a memory configured to store a plurality of second extended display identification data, EDID, information supportable by the display device; and a processor configured to: transmit a first EDID to the source device through the external input interface when the source device is connected to the external input interface; determine the presence or absence of a video signal or an audio signal input from the source device received in the first EDID; and change the first EDID and transmit the changed first EDID to the source device through the external input interface based on a determination that there is no video signal or audio signal from the source device, characterized in that: the changed first EDID is a second EDID having a version different from that of the first EDID and that has not yet been provided to the source device, and the change of first EDID is repeated until the second EDID that has not been provided to the source device among the plurality of second EDID information exists in the memory, and when there is no remaining EDID of the plurality of second EDID information that has not yet been provided to the source device, determine that an error has occurred. an external input interface connected to a source device; a memory configured to store a plurality of second extended display identification data, EDID, information supportable by the display device; and a processor configured to: transmit a first EDID to the source device through the external input interface when the source device is connected to the external input interface; determine the presence or absence of a video signal or an audio signal input from the source device received in the first EDID; and change the first EDID and transmit the changed first EDID to the source device through the external input interface based on a determination that there is no video signal or audio signal from the source device, characterized in that: the changed first EDID is a second EDID having a version different from that of the first EDID and that has not yet been provided to the source device, and the change of first EDID is repeated until the second EDID that has not been provided to the source device among the plurality of second EDID information exists in the memory, and when there is no remaining EDID of the plurality of second EDID information that has not yet been provided to the source device, determine that an error has occurred. transmit a first EDID to the source device through the external input interface when the source device is connected to the external input interface; determine the presence or absence of a video signal or an audio signal input from the source device received in the first EDID; and change the first EDID and transmit the changed first EDID to the source device through the external input interface based on a determination that there is no video signal or audio signal from the source device, characterized in that: the changed first EDID is a second EDID having a version different from that of the first EDID and that has not yet been provided to the source device, and the change of first EDID is repeated until the second EDID that has not been provided to the source device among the plurality of second EDID information exists in the memory, and when there is no remaining EDID of the plurality of second EDID information that has not yet been provided to the source device, determine that an error has occurred. the changed first EDID is a second EDID having a version different from that of the first EDID and that has not yet been provided to the source device, and the change of first EDID is repeated until the second EDID that has not been provided to the source device among the plurality of second EDID information exists in the memory, and when there is no remaining EDID of the plurality of second EDID information that has not yet been provided to the source device, determine that an error has occurred.