This welding control device which controls a welding condition when arc welding is performed on a groove having a root gap, comprises: a first detection means for detecting, from a captured image of a fused section formed in the groove, the position of the tip of the fused section with respect to a direction in which the welding progresses; a second detection means for detecting the position of an end of a to-be-welded object for defining the root gap; a determination means for determining the relationship between the position of the end and the position of the tip of the fused section; and a control means for controlling the welding condition according to the determination result.