A transmission device includes an image processing unit that controls transmission of a first packet including region information regarding a region detected from an image and controls transmission of a second packet for each of lines in which at least the region has been detected in the image. The second packet comprises a header including information regarding the line, and a payload including region data concerning a partial region corresponding to the line, out of the region, in which the header includes: identification information of the data included in the payload; an error correction code of the information included in the header; and an extension region provided so as to be interposed between the identification information and the error correction code, and information indicating whether or not the region data is included in the payload corresponding to the header is set in at least a part of the extension region.