A method and a device for carrying out a work operation, on a workpiece continually moving forward on a conveying device, by an industrial robot moving along with the workpiece during a common run though a work path are provided. The industrial robot is displaceable along a separate longitudinal guide next to the conveying device. During the common run a base part of the industrial robot is rigidly coupled to a workpiece carrier, and the base part floats relative to a bogie running in the longitudinal guide. The industrial robot includes an exchangeable tool which, at the beginning of the common run through the working path, is a scanner tool connected to a working arm of the industrial robot. A relative position between the work piece and the workpiece carrier is determined from the reference coordinate system of the industrial robot.