A wireless communication system comprising: a first base station apparatus; a second base station apparatus; and a mobile station apparatus configured to communicate with the first and second base station apparatuses (A11, A21), wherein the first base station apparatus is configured to communicate with the mobile station apparatus, the second base station apparatus is configured to communicate with the mobile station apparatus using a plurality of common frequency bands and at least one of dedicated frequency bands, the plurality of the common frequency bands being used by the first and second base station apparatuses (A11, A21), the at least one of the dedicated frequency bands being not used by the first base station apparatus, the second base station apparatus comprises a communication band selection unit configured to select all of the plurality of the common frequency bands in case that a radio quality of a part of the plurality of the common frequency bands in the mobile station apparatus is greater than a predetermined threshold value, and to select the at least one of the dedicated frequency bands in case that the radio quality is less than the predetermined threshold value, at least one of the mobile station apparatus and the second base station apparatus comprises a mobile station radio control unit configured to control a first communication between the mobile station apparatus and the second base station apparatus so as to use all of the plurality of the common frequency bands, the first communication using a carrier aggregation technology, the first communication being performed in case that the radio quality is greater than the predetermined threshold value, and to control a second communication so as to use the at least one of the dedicated frequency bands, the second communication being performed in case that the radio quality is less than the predetermined threshold value, and the communication band selection unit and the mobile station radio control unit are configured to use, as a part of the plurality of the common frequency bands, one frequency band whose frequency is lowest among the plurality of the common frequency bands. a first base station apparatus; a second base station apparatus; and a mobile station apparatus configured to communicate with the first and second base station apparatuses (A11, A21), wherein the first base station apparatus is configured to communicate with the mobile station apparatus, the second base station apparatus is configured to communicate with the mobile station apparatus using a plurality of common frequency bands and at least one of dedicated frequency bands, the plurality of the common frequency bands being used by the first and second base station apparatuses (A11, A21), the at least one of the dedicated frequency bands being not used by the first base station apparatus, the second base station apparatus comprises a communication band selection unit configured to select all of the plurality of the common frequency bands in case that a radio quality of a part of the plurality of the common frequency bands in the mobile station apparatus is greater than a predetermined threshold value, and to select the at least one of the dedicated frequency bands in case that the radio quality is less than the predetermined threshold value, at least one of the mobile station apparatus and the second base station apparatus comprises a mobile station radio control unit configured to control a first communication between the mobile station apparatus and the second base station apparatus so as to use all of the plurality of the common frequency bands, the first communication using a carrier aggregation technology, the first communication being performed in case that the radio quality is greater than the predetermined threshold value, and to control a second communication so as to use the at least one of the dedicated frequency bands, the second communication being performed in case that the radio quality is less than the predetermined threshold value, and the communication band selection unit and the mobile station radio control unit are configured to use, as a part of the plurality of the common frequency bands, one frequency band whose frequency is lowest among the plurality of the common frequency bands.