Abstract: The holding device for conveying container bodies open at both ends made of ferromagnetic material on a conveyor has at least one permanent magnet for generating magnetic forces necessary to hold the container body on it, a supporting member attachable with the conveyor and two framework components (one of which may be made slidable) held spaced from each other aligned in the longitudinal direction of the supporting member. Alternatively in two specific examples of our invention the permanent magnet is provided in the vicinity of the framework components and the supporting member is insertable in the container body or the permanent magnet is provided on the supporting member or it is the supporting member and an electrode distinct from the supporting member is insertable in the container body. The framework members have a substantially U-shape cross section and are arranged so that their free side pieces on each side thereof parallel the longitudinal direction of the supporting member.