In a disclosed laser module, a usage amount of organic adhesive is set to no more than 1.0 g/ml. Thus, an equilibrium density of outgas components from the adhesive after an air removal treatment is less than 1000 ppm. In another laser module, a heat sink at which a semiconductor laser element is adhered on a submount, an electrode terminal wire-connected with the laser element, a photodiode wire-connected with the electrode terminal, and a zeolite adsorbent are fixedly provided on a stem. These are ring-welded in a container in a dry air atmosphere (80% nitrogen, 20% oxygen). In still another laser module, sixteen multiplexed lasers are disposed in a container. The container is connected with an air circulation apparatus, which is provided with a filter for removing contaminants, a rotary pump for circulating inert gas, and a valve for controlling replenishment of the gas.