A communication system comprising a user terminal and a plurality of base stations, the communication system carrying out CoMP (Coordinated Multi-Point) communication where a plurality of wireless signals are transmitted to the user terminal through a plurality of cells including a serving cell and a plurality of coordinated cells except for the serving cell, the plurality of wireless signals containing the same data, the serving cell providing a wireless resource for exchanging control information to control communication between the user terminal and the base stations, the communication system further comprising: a selector that selects a reference coordinated cell among the plurality of coordinated cells, the reference coordinated cell being a reference to adjust a serving-cell phase representing a phase on a complex plane that a wireless signal transmitted through the serving cell has, the user terminal comprising an adjusting parameter obtainer that obtains an adjusting parameter to adjust the serving-cell phase using the wireless signal received through the selected reference coordinated cell and the wireless signal received through the serving cell; and a transmitter (302, 303, 304, 305) that transmits the control information including the obtained adjusting parameter to a serving base station that provides the serving cell and that is one of the plurality of base stations, the serving base station comprising a controller (203, 215) that receives the control information and controls execution of the CoMP communication such that the serving-cell phase is adjusted on the basis of the adjusting parameter included in the received control information. a selector that selects a reference coordinated cell among the plurality of coordinated cells, the reference coordinated cell being a reference to adjust a serving-cell phase representing a phase on a complex plane that a wireless signal transmitted through the serving cell has, the user terminal comprising an adjusting parameter obtainer that obtains an adjusting parameter to adjust the serving-cell phase using the wireless signal received through the selected reference coordinated cell and the wireless signal received through the serving cell; and a transmitter (302, 303, 304, 305) that transmits the control information including the obtained adjusting parameter to a serving base station that provides the serving cell and that is one of the plurality of base stations, an adjusting parameter obtainer that obtains an adjusting parameter to adjust the serving-cell phase using the wireless signal received through the selected reference coordinated cell and the wireless signal received through the serving cell; and a transmitter (302, 303, 304, 305) that transmits the control information including the obtained adjusting parameter to a serving base station that provides the serving cell and that is one of the plurality of base stations, the serving base station comprising a controller (203, 215) that receives the control information and controls execution of the CoMP communication such that the serving-cell phase is adjusted on the basis of the adjusting parameter included in the received control information.