To obain a high-gain, high-efficiency and low-strain amplifying device, by a method wherein the device is constituted into such a structure that the impedances of prescribed wirings in the wiring rows on the input and output sides of the device are different from those of the wirings other than the prescribed wirings and the distribution of the impedances is made to exist in the wiring rows on at least one side of the wiring rows on the input and output sides.

Input power, which is fed through an input terminal 213, is branched by a plurality of wires 101 via an input side impedance matching circuit 205 and the branched input powers are distributively inputted in a field-effect transistor 202. Moreover, the output power amplified in the transistor 202 is synthesized by a plurality of wires 102 and the synthesized output power is transmitteds to an output wiring 208 via an output impedance matching circuit 207. The impedances of the wires 101 are respectively changed in the wiring rows consisting of the wires 101 on the input side of an amplifying device, and a current is evenly made to flow through each wire 101. Moreover, as the impedances of the wires 102 are respectively changed in the wiring rows consisting of the wires 102 on the output side of the device, the current is evenly made to flow through each wire 102.