A transmission power control device is able to capture the serving sector measurement information of a mobile station with respect to a serving sector and the neighboring sector measurement information of the mobile station with respect to a neighboring sector. The transmission power control device selects a power control mode based on a decision as to whether or not the neighboring sector measurement information has been captured in an applied time in the past. The power level of a mobile station is determined based on the selected power control mode. Thus, it is possible to reduce inter-cell interference and inter-sector interference because the power level of a mobile station is determined in light of communication environments, even though the mobile station is connected with a base station in an LTE-based communication system which cannot always detect the neighboring sector measurement information.