A radio communication system comprising: (a) a first base station configured to perform radio communication including at least a first downlink communication with a first mobile station; and (b) a second base station configured to perform radio communication including at least a second downlink communication with a second mobile station, (c) a first resource adjustment means (1-1, 13), arranged in the first base station, for determining radio resources to be allocated to the first downlink communication from a radio resource region shared between the first and second base stations; (d) a quality estimation means, arranged in the first base station or a higher-level network (4, 5) to which the first and second base stations (1-1, 1-2) are connected, for estimating communication quality of the first downlink communication, assuming that radio resources allocatable to the first downlink communication have been limited to a part of the radio resource region; (e) a first resource division means (1-1, 12), arranged in the first base station or the higher-level network (4, 5), for limiting, to a first radio resource segment which is a part of the radio resource region, radio resources in response to estimating that communication quality of the first downlink communication using the limited first radio resource segment is improved over the communication quality of the first downlink communication when using the entire range of the radio resource region that is shared with the second base station; (f) a second resource adjustment means (1-2, 13), arranged in the second base station, for determining radio resources to be allocated to the second downlink communication from the radio resource region; (g) a detection means, arranged in the second base station or the higher-level network (4, 5), for detecting execution of resource division for limiting radio resources used for the first downlink communication to the first radio resource segment; and (h) a second resource division means (1-2, 12), arranged in the second base station or the higher-level network (4, 5), for limiting, to a second radio resource segment which is a part of the radio resource region and different from the first radio resource segment, radio resources allocatable to the second downlink communication by the second resource adjustment means (1-2, 13) in response to detection of the resource division. (a) a first base station configured to perform radio communication including at least a first downlink communication with a first mobile station; and (b) a second base station configured to perform radio communication including at least a second downlink communication with a second mobile station, (c) a first resource adjustment means (1-1, 13), arranged in the first base station, for determining radio resources to be allocated to the first downlink communication from a radio resource region shared between the first and second base stations; (d) a quality estimation means, arranged in the first base station or a higher-level network (4, 5) to which the first and second base stations (1-1, 1-2) are connected, for estimating communication quality of the first downlink communication, assuming that radio resources allocatable to the first downlink communication have been limited to a part of the radio resource region; (e) a first resource division means (1-1, 12), arranged in the first base station or the higher-level network (4, 5), for limiting, to a first radio resource segment which is a part of the radio resource region, radio resources in response to estimating that communication quality of the first downlink communication using the limited first radio resource segment is improved over the communication quality of the first downlink communication when using the entire range of the radio resource region that is shared with the second base station; (f) a second resource adjustment means (1-2, 13), arranged in the second base station, for determining radio resources to be allocated to the second downlink communication from the radio resource region; (g) a detection means, arranged in the second base station or the higher-level network (4, 5), for detecting execution of resource division for limiting radio resources used for the first downlink communication to the first radio resource segment; and (h) a second resource division means (1-2, 12), arranged in the second base station or the higher-level network (4, 5), for limiting, to a second radio resource segment which is a part of the radio resource region and different from the first radio resource segment, radio resources allocatable to the second downlink communication by the second resource adjustment means (1-2, 13) in response to detection of the resource division.