A cam mechanism for actuating a selector shaft, in particular for a single-motor gearshift actuation device, in particular to carry out a selecting movement of the selector shaft, comprising a cylindrical outer body having an inner circumferential surface and a cam track disposed on the inner circumferential surface and having an endless periodicity in a circumferential direction with at least one highest point and at least one lowest point, an inner body having at least one sliding guide extending in a direction perpendicular to the circumferential direction, at least one guide element disposed in the cam track and in the sliding and suitable for transmitting a movement of the guide element in a direction perpendicular to the circumferential direction to a selector shaft.