Fastening device for backrest elements of a backrest of a seat arrangement in a motor vehicle, wherein the backrest has two backrest elements arranged movably independently of each other about a pivot axis running transversely with respect to the direction of travel, wherein each backrest element comprises an outer bearing point and a central bearing point for forming the pivot axis, wherein the outer bearing point comprises a bearing spindle secured on the respective backrest element and a counter bearing element secured on the body of the motor vehicle, wherein the bearing axis of each backrest element can be mounted in the counter bearing element in a preassembly position and in a final assembly position and, for this purpose, has an end portion for attaching to the respective backrest element, a cylindrical bearing portion for mounting in the final assembly position, and a preassembly bearing portion for the supported mounting in the preassembly position, wherein the preassembly bearing portion extends in the form of an elongate latch radially on one side from the cylindrical bearing portion and comprises a rectangular guide portion with side surfaces, which are aligned parallel to each other, for mounting in the preassembly position, wherein the counter bearing element has a housing portion with a keyhole-like passage opening, which is formed by a cylindrical bearing recess corresponding to the bearing portion and a rectangular slot region for receiving the guide portion in the preassembly position, wherein the central bearing point comprises a bearing spindle secured on the respective backrest element and a counter bearing element secured on the body of the motor vehicle, wherein the bearing spindle of each backrest element can be mounted lying opposite in the counter bearing element in a preassembly position and in a final assembly position and, for this purpose, comprises an end portion for attaching to the respective backrest element, a preassembly bearing portion with a rectangular guide portion for mounting in the preassembly position, and a cylindrical bearing portion for mounting in the final assembly position, wherein the counter bearing element comprises a housing portion for the mounting and receiving of the two adjacently arranged bearing spindles and, for this purpose, comprises two wall portions each having a cylindrical bearing recess with respect to the bearing portions and in each case a rectangular slot region for receiving the guide portion in the preassembly position, and a panel with a covering element and a clip which, for the pushing apart and the latched holding of the cylindrical, mutually facing end portions of the bearing spindles, which are inserted lying opposite in the counter bearing element, is insertable starting from the preassembly position into the final assembly position in the housing portion. wherein each backrest element comprises an outer bearing point and a central bearing point for forming the pivot axis, wherein the outer bearing point comprises a bearing spindle secured on the respective backrest element and a counter bearing element secured on the body of the motor vehicle, wherein the bearing axis of each backrest element can be mounted in the counter bearing element in a preassembly position and in a final assembly position and, for this purpose, has an end portion for attaching to the respective backrest element, a cylindrical bearing portion for mounting in the final assembly position, and a preassembly bearing portion for the supported mounting in the preassembly position, wherein the preassembly bearing portion extends in the form of an elongate latch radially on one side from the cylindrical bearing portion and comprises a rectangular guide portion with side surfaces, which are aligned parallel to each other, for mounting in the preassembly position, wherein the counter bearing element has a housing portion with a keyhole-like passage opening, which is formed by a cylindrical bearing recess corresponding to the bearing portion and a rectangular slot region for receiving the guide portion in the preassembly position, wherein the central bearing point comprises a bearing spindle secured on the respective backrest element and a counter bearing element secured on the body of the motor vehicle, wherein the bearing spindle of each backrest element can be mounted lying opposite in the counter bearing element in a preassembly position and in a final assembly position and, for this purpose, comprises an end portion for attaching to the respective backrest element, a preassembly bearing portion with a rectangular guide portion for mounting in the preassembly position, and a cylindrical bearing portion for mounting in the final assembly position, wherein the counter bearing element comprises a housing portion for the mounting and receiving of the two adjacently arranged bearing spindles and, for this purpose, comprises two wall portions each having a cylindrical bearing recess with respect to the bearing portions and in each case a rectangular slot region for receiving the guide portion in the preassembly position, and a panel with a covering element and a clip which, for the pushing apart and the latched holding of the cylindrical, mutually facing end portions of the bearing spindles, which are inserted lying opposite in the counter bearing element, is insertable starting from the preassembly position into the final assembly position in the housing portion.