An X-ray device has a detector which is arranged on a mobile unit and is assigned to a first positioning unit. An X-ray source is arranged on an arcuate second positioning unit. The positioning of the first and second positioning units can be matched to one another in the course of their movements. The first positioning unit has at least one articulated arm and the second positioning unit has a first and a second arc-shaped positioning element. The first and second positioning units are arranged separately from one another on a movable unit.