When measurement results of received radio wave intensities of wireless base stations, which demands a soft handoff, are received from a wireless terminal in a wireless communication system and when a base station controller attempts to acquire a traffic channel in a wireless base station, via which a wireless communication path will be added, in the state in which the channel resource usage rate of that wireless base station is over a threshold, a traffic channel may be acquired only if the ratio between the radio wave intensity of the wireless base stations establishing communication paths and the radio wave intensity of the wireless base station via which a communication path will be added is higher than a threshold or if the difference between the radio wave intensity of the wireless base stations and the radio wave intensity of the wireless base station smaller than a threshold.