An optical transmitter module includes a semiconductor laser device, optical modulator, temperature adjusting device which includes a substrate, a first installation part and a second installation part, a package having a bottom surface opposite to a back surface of the substrate, the package housing the semiconductor laser device, the optical modulator, and the temperature adjusting device; and a middle block disposed between a first temperature controlling element a the second temperature controlling element, the middle block having a back surface directly or indirectly fastened to a principal surface of the substrate.