A user equipment in a radio communication system including a base station and the user equipment, the user equipment including: a storage unit that includes a soft buffer region that is used in a retransmission control of downlink data that is received from the base station; and a retransmission control unit that divides a partial region of the soft buffer region into a plurality of sub-buffer regions, and performs the retransmission control of the downlink data that is received from the base station by using one or a plurality of sub-buffer regions among the plurality of sub-buffer regions.