An electric plug-in device, which is suitable for plugging into an electric receiving device, has an inner conductor and an insulating body that encloses the inner conductor. The plug-in device includes a retaining element which can be firmly connected indirectly, in particular with the help of a housing wall, or directly to the receiving device; a sliding element which can be moved axially along a longitudinal axis of the inner conductor relative to the retaining element includes the internal conductor and the insulating body. When the plug-in device is plugged into the receiving device, the sliding element protrudes into a receiving portion of the receiving device. A spring device exerts an axially active spring force on the sliding element in the direction of the receiving device when the plug-in device is plugged into the receiving device.