There are included a Wilkinson divider/combiner dividing an input signal, amplifying elements amplifying outputs of the Wilkinson divider/combiner, and a Wilkinson divider/combiner combining outputs of respective amplifying elements. A variable capacitor element is connected to a branch point of a signal transmission path in the Wilkinson divider/combiner. A capacitance value of the variable capacitor element is controlled in correspondence with a frequency of an input signal, whereby a matching frequency is corrected to increase an operating frequency band.