There is provided a radio base station apparatus which is capable of increasing the probability of detection of a first path even if a radio transmission path fluctuates due to fading or the like, and of downsizing and reducing the cost of mobile radio terminal apparatus. SIR estimators 13-1 through 13-N calculate reception SIRs for respective subcarriers from output signals from pilot demodulators 12-1 through 12-N. SIR averager 14 averages the SIRs for the respective subcarriers to calculate an SIR for the overall signal. Based on the calculated SIR, threshold value setting unit 15 sets a threshold value for a path search. First path detector 19 conducts a path search based on the threshold set by threshold value setting unit 15. Arrival time calculator 21 calculates an arrival time based on a first path detected by first path detector 19.