<p>An inexpensive module structure capable of driving an LD array with low stress at a suitable temperature is obtained. The laser module includes: a heat sink (3) that releases heat from a member in contact with the heat sink (3); a sub-mount substrate (4) that is disposed on the heat sink (3) and made of an insulating material; a feeding layer (5A) that is disposed on the sub-mount substrate (4); and a laser diode array (6) that has a plurality of light-emitting portions disposed on the feeding layer (5A) in a parallel arrangement. A linear expansion coefficient of the sub-mount substrate (4) is made smaller than a linear expansion coefficient of the laser diode array (6), and the linear expansion coefficient of the sub-mount substrate (4) in a state connected to the heat sink (3) having a larger linear expansion coefficient than the laser diode array (6) is set to fall within a predetermined range including the linear expansion coefficient of the laser diode array (6).</p>
