An actuating device for selecting gear steps of a shift-by-wire gearshift transmission with a base housing, a selection lever, a mechanical transmission means for actuating the parking lock, and with a coupling element are arranged between the selection lever and the transmission means. The transmission means is selectively actuated by the coupling element only during selection and/or deselection of the parking lock position on the selection lever. The coupling element has an end which is linearly guided in a slot and an end which is pivotally guided in certain sections in the base housing. The coupling element and the selection lever are kinematically coupled with each other by way of a swivel support. The structure and the installation of the mechanical transmission linkage required for selectively actuating the transmission means to the parking lock can be simplified. The mechanical transmission linkage provides a smoothly operating haptic without significant play and can be used without complex changes also for actuating devices having more than one shift gate.