variable gain amplifying means having a plurality of coarse adjustment variable amplifying sections and fine adjustment variable gain amplifying sections, to which at least one received signal is inputted, and amplifying the inputted received signal with controlled gain for output;

memory means for storing a history of gain control with regard to said variable gain amplifying means; and

gain control means for controlling the gain of said variable gain amplifying means on the basis of signal strength of said received signal and the history stored in said memory means,

wherein: said gain control means individually controls gain of each variable gain amplifying section in such a manner that gain fluctuation frequency of said coarse adjustment variable gain amplifying section arranged on an input side becomes lower than gain fluctuation frequency of other variable gain amplifying section arranged on an output side,

wherein said gain control means holds a first threshold and a second threshold with regard to said signal strength, and on the basis of the history stored in said memory means, in a case where said signal strength is determined to fluctuate exceeding a first fluctuation width determined by said first and second thresholds, controls gain of said coarse adjustment variable gain amplifying section, and

wherein the first threshold and the second threshold is predetermined so that the first fluctuation width between the first threshold and the second threshold is larger than a second fluctuation width of a normalized received signal power obtained from a relationship between a cumulative probability distribution and a spreading bandwidth of the received signal.