To properly control a signal to interference ratio (SIR) using a block error rate being a clear index as a reference, and in such a way that instantaneous fluctuations of interference power can be immediately dealt with, in a radio communication system for re-using frequencies in a geographically dense conditions such as a CDMA system.

A reference SIR calculating section 34 calculates a control value for correcting instantaneous fluctuation of the SIR on the basis of a result obtained by making an error hard decision result for each receiving block by an error inspection section 33 into soft decision, by a maximum likelihood path metric for each reception block to be obtained from a Viterbi decoding section 32. At the same time, the section 34 calculates the control value of an SIR for ensuring a predetermined block error rate on the basis of a result of estimating the block error rate using a target value TBLER as a reference. The section 34 totals these values and outputs the totaled value to a down stream transmission power indicating section 35.