The present invention is designed to use radio resources effectively and improve the throughput of a radio communication system even when a plurality of small cells are placed densely. A radio base station controls the connecting cell of a user terminal, and has a selection section that selects candidate cells, the received power and/or the received quality of which in the user terminal is equal to or greater than a predetermined value, and a determining section that calculates the amount of data to transmit to serving user terminals, for each candidate cell, by taking into account the frequency band that is used, and determines a candidate cell where the amount of data is small, as the connecting cell of the user terminal.