Defects such as porosity, underfill, and magnesium loss occur during laser welding of 5182 aluminum alloy. To compensate for these problems, AA5356 filler wire was used in our present work. To investigate the weld characteristics of the filler wire, experiments were performed with laser power, welding speed, and wire feed rate as the control variables. Bead appearance, bead shape, penetration depth, tensile strength, and the Erichsen ratio were observed as weld characteristic variables. The range of full penetration was reduced as laser power decreased and welding speed and wire feed rate increased. Without filler wire, full penetration was formed under all conditions. However, with filler wire, the range of conditions necessary to form full penetration was reduced as the wire feed rate increased because the heat input was used to melt both of the filler wire and the base metal. Filler wire increased the tensile strength and the Erichsen ratio. Using analysis of variance (ANOVA), it was shown that laser power had a greater influence on tensile strength and the Erichsen ratio among the three control variables. It was also found that tensile strength was closely related to the Erichsen ratio because the coefficient of correlation was 0.899.