A radio base station communicating with user terminals (300, 400) and being configured to execute wireless transmission to the user terminals using resources that are the same as resources used by a low-power radio base station having a maximum transmission power less than a maximum transmission power of the radio base station and forming a second cell (Cp) within a first cell (Cm) formed by the radio base station, the radio base station being configured to collaborate with the low-power radio base station for inter-cell interference control, the radio base station comprising: a radio communicator configured to execute wireless communication with user terminals connected with the radio base station; and a transmission power controller configured to control downlink transmission power used by the radio communicator for transmission to the user terminals; wherein the transmission power controller is configured to cause the radio communicator to operate at a first downlink transmission power at first resources among said resources, and to cause the radio communicator to operate at a second downlink transmission power that is lower than the first downlink transmission power at second resources among said resources, and wherein the transmission power controller is configured to adjust the second downlink transmission power in accordance with a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with at least one of the radio base station and the low-power radio base station, a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with the low-power radio base station, a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with the radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with at least one of the radio base station and the low-power radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with the radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with the low-power radio base station, the number of downlink resource blocks allocated to user terminals that are connected with the low-power radio base station and that are capable of executing interference rejection combining, or the number of downlink resource blocks allocated to user terminals that are connected with at least one of the radio base station and the low-power radio base station and that are capable of executing interference rejection combining. a radio communicator configured to execute wireless communication with user terminals connected with the radio base station; and a transmission power controller configured to control downlink transmission power used by the radio communicator for transmission to the user terminals; wherein the transmission power controller is configured to cause the radio communicator to operate at a first downlink transmission power at first resources among said resources, and to cause the radio communicator to operate at a second downlink transmission power that is lower than the first downlink transmission power at second resources among said resources, and wherein the transmission power controller is configured to adjust the second downlink transmission power in accordance with a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with at least one of the radio base station and the low-power radio base station, a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with the low-power radio base station, a proportion of the number of user terminals capable of executing interference rejection combining to the total number of user terminals connected with the radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with at least one of the radio base station and the low-power radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with the radio base station, a proportion of the downlink traffic amount for user terminals capable of executing interference rejection combining to the total downlink traffic amount for user terminals connected with the low-power radio base station, the number of downlink resource blocks allocated to user terminals that are connected with the low-power radio base station and that are capable of executing interference rejection combining, or the number of downlink resource blocks allocated to user terminals that are connected with at least one of the radio base station and the low-power radio base station and that are capable of executing interference rejection combining.