To provide means of improving a transmission performance while reducing costs.

A semiconductor device comprises a circuit board 11, an MMIC chip 121, transmission lines 13a-13o, first wires W1-W12 and second wires W13-W15. The MMIC chip 121 is provided on the circuit board 11. The transmission lines 13a-13o are formed on the circuit board 11 and connected to the MMIC chip 121. The first wires W1-W12 are wires with one ends being bonded to terminals of the MMIC chip 121 and the other ends being bonded to terminals of the transmission lines 13a-13l after bonding of the one ends. The second wires W13-W15 are wires with one ends being bonded to terminals of the transmission lines 13m-13o and the other ends being bonded to the terminals of the MMIC chip 121 after bonding of the one ends.