a low noise amplifier which amplifies a radio signal;

a quadrature demodulator which demodulates the amplified radio signal into a baseband signal;

a variable gain amplifier which amplifies the baseband signal;

an executing unit configured to execute feedback the amplified baseband signal; and

a first gain controller which controls a first gain of the low noise amplifier and a second gain of the variable gain amplifier, the first gain controller comprising,

a signal intensity detector which detects an intensity of the amplified baseband signal,

a gain selector which selects a preset gain from a plurality of preset gains which are set for the low noise amplifier, based on the detected intensity,

a timing controller which controls timing of switching the first gain and the second gain to the selected preset gain,

a gain control signal output unit configured to output a gain control signal which controls the first gain according to the selected preset gain at a time-interval according to the controlled timing, and

a second gain controller which controls the second gain and does not controls the first gain if the time-interval is not longer than a preset time-interval;

wherein the timing controller comprises,

a measurement unit configured to measure time when the first gain is switched, and calculate the time-interval elapsing from a previous adjacent time when the first gain was switched to the measured time,

a comparator configured to compare the time-interval with the preset time-interval, and

the gain control signal output unit outputs the gain control signal to the low noise amplifier if the time-interval is longer than the preset time-interval.