An OAM multiplexing communication system that uses a plurality of orbital angular momentum,OAM, modes and multiplexes signals of the plurality of OAM modes, wherein the OAM multiplexing communication system is characterized by: a transmitting station including: a transmitting antenna that is configured to use an M-UCA in which a plurality of uniform circular arrays (UCAs) having different diameters are concentrically disposed, each UCA having a plurality of antenna elements disposed circularly at an equal interval; and an OAM mode generation unit that is configured to simultaneously generate the plurality of OAM modes from each UCA of the transmitting antenna; and a receiving station including: a receiving antenna that has a configuration equivalent to the M-UCA; an OAM mode separation unit that is configured to separate signals received by each UCA of the receiving antenna for each of the plurality of OAM modes; and a received signal processing unit that is configured to estimate channel information for each OAM mode separated from the signals received by the each UCA of the receiving antenna, and is configured to perform an equalization process for each OAM mode by using a receiving weight calculated from said channel information, wherein the received signal processing unit is configured to estimate, for each OAM mode, channel information of one or more other OAM modes causing interference to the respective OAM mode and is configured to calculate the receiving weight of the respective OAM mode by using the channel information of the respective OAM mode and the channel information of said one or more other OAM modes. a transmitting station including: a transmitting antenna that is configured to use an M-UCA in which a plurality of uniform circular arrays (UCAs) having different diameters are concentrically disposed, each UCA having a plurality of antenna elements disposed circularly at an equal interval; and an OAM mode generation unit that is configured to simultaneously generate the plurality of OAM modes from each UCA of the transmitting antenna; and a transmitting antenna that is configured to use an M-UCA in which a plurality of uniform circular arrays (UCAs) having different diameters are concentrically disposed, each UCA having a plurality of antenna elements disposed circularly at an equal interval; and an OAM mode generation unit that is configured to simultaneously generate the plurality of OAM modes from each UCA of the transmitting antenna; and a receiving station including: a receiving antenna that has a configuration equivalent to the M-UCA; an OAM mode separation unit that is configured to separate signals received by each UCA of the receiving antenna for each of the plurality of OAM modes; and a received signal processing unit that is configured to estimate channel information for each OAM mode separated from the signals received by the each UCA of the receiving antenna, and is configured to perform an equalization process for each OAM mode by using a receiving weight calculated from said channel information, wherein a receiving antenna that has a configuration equivalent to the M-UCA; an OAM mode separation unit that is configured to separate signals received by each UCA of the receiving antenna for each of the plurality of OAM modes; and a received signal processing unit that is configured to estimate channel information for each OAM mode separated from the signals received by the each UCA of the receiving antenna, and is configured to perform an equalization process for each OAM mode by using a receiving weight calculated from said channel information, wherein the received signal processing unit is configured to estimate, for each OAM mode, channel information of one or more other OAM modes causing interference to the respective OAM mode and is configured to calculate the receiving weight of the respective OAM mode by using the channel information of the respective OAM mode and the channel information of said one or more other OAM modes.