An optical module having: a first transmission line and a second transmission line, both connected in series to transmit electrical signals; a laser diode element; an optical modulator element; a termination resistance element for impedance matching; a first bonding wire connecting one end of the first transmission line and the optical modulator element; and a second bonding wire connecting the optical modulator element and the termination resistance element. The resistance value of the termination resistance element is set to stay in a range from 40 to 60 Ω, the characteristic impedance of the second transmission line is set to 50 Ω, and the characteristic impedance of the first transmission line is set to stay in a range from 20 to 30 Ω.