Laser-arc hybrid welding is considered to be an efficient, practical welding process because its deposited metal from welding wire can increase gap-bridging ability and prevent welding defects such as undercutting or underfilling. The deposition rate from welding wire, however, can not be adjusted independently on the welding current under the stable welding conditions because it is necessary to maintain a constant arc voltage. Although the combination of a higher deposition rate and a lower welding current is sometimes needed, for example during the welding of a thin sheet, a high deposition rate generally accompanies with a high welding current in the conventional laser-arc hybrid welding. In order to solve the above mentioned problems, the authors have proposed a novel method, a filleradded laser-arc hybrid welding (FLA welding) process, to increase a deposition rate without increasing the welding current itself in the welding of aluminum alloy. As a result, gap-bridging ability can be increased in the welding of both thin and thick plates. In this paper, the welding of aluminum alloy butt joints by using FLA welding process is discussed.