In a semiconductor laser module, in order to sufficiently reduce the thermal stress arising in a due to the bonding of elements when they are packaged and to improve the yield of production, the semiconductor laser module is provided with a semiconductor laser element, a submount bonded to the semiconductor laser element with a solder layer in-between and thereby mounted with it, and a base mounted with this submount with another solder layer in-between. Herein, T/W0.15 holds, where W is the width of the submount in the direction orthogonal to the optical axis of the semiconductor laser element and T is the thickness of the submount.