A receiving device and a communication system wherein the frequency usage efficiency is raised to improve the communication throughput. The receiving device comprises a receiving unit that receives multicarrier signals in which a plurality of subcarriers are divided into a plurality of subcarrier blocks (frequency blocks) each including at least one subcarrier and in which signals to be transmitted to receiving devices are allocated on a subcarrier block basis; an estimating unit that estimates, for each of the subcarrier blocks, quality values indicative of the reception statuses of the signals allocated to the plurality of subcarrier blocks; and a notifying unit that notifies a transmitting device of information indicative of a high quality subcarrier block having a high quality value in the quality values, a quality value in the high quality subcarrier block, and an interval of the subcarrier blocks having the quality value of which a difference from the quality value in the high-quality subcarrier block falls within a predetermined threshold value.