The present invention provides a wireless communication system and a terminal. A base station notifies terminals of an intensity of a received interference power. The terminal controls a transmission power for transmitting data to the base station, which is one of base stations and to which data is to be transmitted, by referencing an intensity of interference power (OSI) notified from base stations to which data is not to be transmitted. The terminal calculates a decision value for increasing/decreasing the transmission power, wherein the decision value is variable according to the current transmission power of the terminal and propagation attenuations between the terminal and the base stations to which data is not to be transmitted, and variably controls the amount of transmission power increase/decrease according to the decision value for increasing/decreasing a transmission power.