A robot welding controller and a robot welding control. It comprises a robot having a welding torch at its tip, a robot controller, a wire feeder, and a welding electric power. It performs welding by moving the welding torch on the basis of a commanded welding line. A contact detecting section detects contact of the wire and the base material. A feed direction switching section switches feed directions of the wire. An arc generation detecting section detects that an arc is generated between the wire and the base material. A waveform control section controls electric power waveforms of plural shapes applied between the wire and the base material. A welding sequence section controls the operations of the contact detecting section, the feed direction switching section, the arc generation detecting section and the waveform control section in block.