For example, in a radio communication system using an OFDMA method, frequency bandwidth allocated to each sector is modified according to, for example, the number of terminals existing in each sector, and the effective utilization of radio sources is promoted. A radio base station device includes unit to determine the amount allocated to each sector from the amount of radio resources in the base station and unit to switch over the connection states of a plurality of radio resources obtained by dividing the entire radio resources that can be allocated to each sector in the base station according to the determined amount of allocation.