A mobile communication method comprising: a step of, when communication of a mobile station in a connected state in a first cell (CELL#1) under control of a first radio station is performed through an EPS bearer formed of a data radio bearer between the mobile station and the first radio base station and an S1-U bearer between the first radio base station and a gateway device, and if a second cell (CELL#10) under control of a second radio base station is located in a coverage of the first cell (CELL#1) causing the first radio base station to send the mobile station a setting change signal containing information correlating identification information on the EPS bearer with identification information on the second cell (CELL#10) based on a result of a radio measurement on the mobile station; a step of causing the mobile station to set a data radio bearer between the mobile station and the second radio base station in response to the setting change signal; and a step of changing the EPS bearer so that the EPS bearer is formed of the data radio bearer between the mobile station and the second radio base station, an S1-U bearer between the second radio base station and the first radio base station, and the S1-U bearer between the first radio base station and the gateway device, the method further comprising: a step of, when the first radio base station removes the second cell (CELL#10), causing the first radio base station to send the mobile station a setting change signal containing information to remove a correlation between the identification information on the EPS bearer and the identification information on the second cell; and a step of changing the EPS bearer so that the EPS bearer is formed of the data radio bearer between the mobile station and the first radio base station and the S1-U bearer between the first radio base station and the gateway device. a step of, when communication of a mobile station in a connected state in a first cell (CELL#1) under control of a first radio station is performed through an EPS bearer formed of a data radio bearer between the mobile station and the first radio base station and an S1-U bearer between the first radio base station and a gateway device, and if a second cell (CELL#10) under control of a second radio base station is located in a coverage of the first cell (CELL#1) causing the first radio base station to send the mobile station a setting change signal containing information correlating identification information on the EPS bearer with identification information on the second cell (CELL#10) based on a result of a radio measurement on the mobile station; a step of causing the mobile station to set a data radio bearer between the mobile station and the second radio base station in response to the setting change signal; and a step of changing the EPS bearer so that the EPS bearer is formed of the data radio bearer between the mobile station and the second radio base station, an S1-U bearer between the second radio base station and the first radio base station, and the S1-U bearer between the first radio base station and the gateway device, the method further comprising: a step of, when the first radio base station removes the second cell (CELL#10), causing the first radio base station to send the mobile station a setting change signal containing information to remove a correlation between the identification information on the EPS bearer and the identification information on the second cell; and a step of changing the EPS bearer so that the EPS bearer is formed of the data radio bearer between the mobile station and the first radio base station and the S1-U bearer between the first radio base station and the gateway device.