An apparatus for moving a pivoting sliding door of a motor vehicle comprising a pivot arm by means of which the pivoting sliding door is connected to a chassis of the motor vehicle; a blocking mechanism (64-52; 54-68), which can adopt a first state in which a sliding of the door is blocked and a pivoting of the door is possible and a second state in which a pivoting of the door is blocked and a sliding of the door is possible; and a transmission mechanism which is coupled to a drive motor, which is accommodated in the pivot arm and which converts the drive force of the drive motor, depending on the state of the blocking mechanism (64-52; 54-68), either into a sliding movement or a pivot movement of the door, wherein the transmission mechanism comprises at least three toothed wheels connected in series such that the transmission mechanism acts in the manner of a planetary transmission, with the toothed wheel at the output side being in engagement directly or indirectly with a mating element fixedly anchored to the door or to the chassis and preferably comprising a toothed belt, a chain or a gear rack, with the blocking mechanism comprising a guide rail (48; 54, 56) provided at the door and extending in the sliding direction and a guide element (46; 58) guided therein and rotationally fixedly connected to the pivot arm, and with the guide rail (46; 54, 56) and the guide element (46; 58) being configured such that a rotation of the guide element (46; 58) relative to the guide rail (48; 54, 56) is only possible in a predefined region of the guide rail (48; 54, 56) and such that a sliding of the guide element (46, 58) relative to the guide rail (48; 54, 56) is only possible outside this region. a pivot arm by means of which the pivoting sliding door is connected to a chassis of the motor vehicle; a blocking mechanism (64-52; 54-68), which can adopt a first state in which a sliding of the door is blocked and a pivoting of the door is possible and a second state in which a pivoting of the door is blocked and a sliding of the door is possible; and a transmission mechanism which is coupled to a drive motor, which is accommodated in the pivot arm and which converts the drive force of the drive motor, depending on the state of the blocking mechanism (64-52; 54-68), either into a sliding movement or a pivot movement of the door, wherein the transmission mechanism comprises at least three toothed wheels connected in series such that the transmission mechanism acts in the manner of a planetary transmission, with the toothed wheel at the output side being in engagement directly or indirectly with a mating element fixedly anchored to the door or to the chassis and preferably comprising a toothed belt, a chain or a gear rack, with the blocking mechanism comprising a guide rail (48; 54, 56) provided at the door and extending in the sliding direction and a guide element (46; 58) guided therein and rotationally fixedly connected to the pivot arm, and with the guide rail (46; 54, 56) and the guide element (46; 58) being configured such that a rotation of the guide element (46; 58) relative to the guide rail (48; 54, 56) is only possible in a predefined region of the guide rail (48; 54, 56) and such that a sliding of the guide element (46, 58) relative to the guide rail (48; 54, 56) is only possible outside this region.