The radio communication system of the present invention includes a radio access network (10) and a radio communication apparatus (60). The radio communication apparatus (60) includes a control unit (61) that, when reconfiguring a radio access bearer between a DCH and an uplink line E-DCH and downlink line HSDPA, sets a start value that is to be used after the reconfiguration in ciphering the radio access bearer, and a transceiver (62) that transmits to the radio access network (10) the start value that was set in the control unit (61) and that is to be used after the reconfiguration.