An image information signal transmitting system for transmitting an image information signals which continuously forms a temporally correlated group of image planes is arranged to divide each image plane portions of the image information signal into a plurality of blocks; and, in determining for every divided block included in each of the image planes the adoption of one of a plurality of information transmitting modes provided for different information transmitting density values, the information transmitting modes for the plurality of blocks of a presently transmitting image plane portion of the signal are determined at least according to the information transmitting modes which hae been used for the plurality of blocks of a previously transmitted image plane portion of the signal.
