A communication system, characterized by: a master communication control device (40 3); and a first slave communication control device (40 4, 40 5) and a second slave communication control device (40 4, 40 5) following the master communication control device (40 3), wherein the first slave communication control device (40 4, 40 5) includes a first acquisition unit that acquires a spectrum grant request following a first scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a first calculation unit that calculates a communication parameter of the second radio system under the first slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), the second slave communication control device (40 4, 40 5) includes a second acquisition unit that acquires a spectrum grant request following a second scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a second calculation unit that calculates a communication parameter of the second radio system under the second slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), and the master communication control device (40 3) includes a processing unit that causes the slave communication control devices (40 4, 40 5) to calculate the communication parameters of the respective second radio systems under the slave communication control devices (40 4, 40 5), in a predetermined slave communication control device order. a master communication control device (40 3); and a first slave communication control device (40 4, 40 5) and a second slave communication control device (40 4, 40 5) following the master communication control device (40 3), wherein the first slave communication control device (40 4, 40 5) includes a first acquisition unit that acquires a spectrum grant request following a first scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a first calculation unit that calculates a communication parameter of the second radio system under the first slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), a first acquisition unit that acquires a spectrum grant request following a first scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a first calculation unit that calculates a communication parameter of the second radio system under the first slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), the second slave communication control device (40 4, 40 5) includes a second acquisition unit that acquires a spectrum grant request following a second scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a second calculation unit that calculates a communication parameter of the second radio system under the second slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), and a second acquisition unit that acquires a spectrum grant request following a second scheme from a second radio system that performs a wireless communication using a radio wave of a frequency band used by a first radio system, and a second calculation unit that calculates a communication parameter of the second radio system under the second slave communication control device (40 4, 40 5) based on an interference margin notified from the master communication control device (40 3), and the master communication control device (40 3) includes a processing unit that causes the slave communication control devices (40 4, 40 5) to calculate the communication parameters of the respective second radio systems under the slave communication control devices (40 4, 40 5), in a predetermined slave communication control device order.