A welding method is employed for an automatic welder, wherein a voltage is applied between a wire (WR) which is moved along a weld path (P0$(1,5)$P1$(1,5)$P2$(1,5)$P3) by a robot, and a welding workpiece (WK), so that an arc is generated from the wire end, and while the wire is successively supplied, the wire end is moved along the weld path by the robot, thereby providing the weld. A multiplicity of welding conditions, including welding voltage, wire feed rate, pre-flow time, crater-treatment time, and post-flow time, are previously stored in a memory, and predetermined welding conditions are selected according to a program. At the welding start point (P1), gas is blown onto the workpiece (WK) during a pre-flow time which is one of the welding conditions selected according to the program. Thereafter, the selected welding voltage is generated, and the wire (WR) is supplied at the selected wire feed rate to start the welding. At the welding end point (P2), a predetermined welding voltage is generated only during the crater-treatment time which is one of the welding conditions selected according to the program. Thereafter, gas is blown on the workpiece (WK) during the post-flow time to effect post-flow processing.