The present invention is aimed to provide a radio base station that communicates with a plurality of mobile stations by a method, such as the space division multiplex, of simultaneously multiplexing into the same frequency, and exercise a control using an index that is different from the SIR and can be used in a control exercised to properly separate signals sent from mobile stations from the same frequency. The reception response vector predicting unit (524), provided in the radio base station of the present invention, obtains a reception response vector that indicates a propagation path of a signal from a mobile station to the radio base station, for each of the plurality of mobile stations. The reception DD ratio calculator (51) obtains two reception response vectors for two mobile stations from the reception response vector predicting unit, calculates a reception DD ratio of (i) a square of a reception response vector of a mobile station to (ii) a square of a reception response vector of the other mobile station, and sends the calculated reception DD ratio to the control unit (80). The control unit (80) judges whether to exercise the transmission power control or the like, based on the reception DD ratio. If the reception DD ratio is not belong to a certain value range, the transmission power control or the like is exercised.