The purpose of this study was to evaluate whether laser welding using an Nd-YAG laser could be used for appliances with an auxiliary spring in pediatric dental clinics. In particular, the elasticity rate and Vickers hardness were examined. A main line and an auxiliary spring were welded using the Nd-YAG laser. The laser welding involved a fiber diameter of 400μm, and a 900 mJ Nd-YAG laser beam, a pulse width of 5 pps and an irradiation time of 1 min. The elastic strain energy for laser welding using the Nd-YAG laser was significantly lower than that of argentums soldering using a flame. In addition, the Vickers hardness was low near the welding area of an auxiliary spring though there was no change in action area of an auxiliary spring. The results of the present study indicated that with laser welding, at the point of joining of the auxiliary spring and the main line, there was less change in the shape of the wire caused by heat when joining in comparison with argentums soldering using a flame, and that it was possible to apply the wire pressure to the teeth continuously.