The variation of the parasitic inductance generated at the output terminal of a transistor in the final stage of a multistage amplifier unit is reduced. One side of the semiconductor chip that includes the final stage transistor is put in contact with the inner wall of a square recess formed in a wiring substrate. The semiconductor chip is positioned and fixed accurately at the bottom of the recess, whereby the drain wire of the transistor is fixed. Then, a chip edge at which the drain electrode is disposed on top of the chip is put in contact with the inner wall of the recess, which is closer to the drain bonding pad. A metallized layer is formed of the same size as that of the chip at the bottom of the recess and a fusion bonding material is supplied on the metallized layer.