A coupling device installed between an output shaft of an electric motor and an input shaft of a reducing gear of an actuator for driving a screen or a hatch that is part of home-automation equipment for closure, solar protection, or projection and which includes a first member rotatably secured to the output shaft, and which is provided with at least one longitudinal outer groove, and a second member rotatably secured to the input shaft, and which is provided with at least one longitudinal outer groove and wherein the coupling device further includes an element for coupling the first and second members together in rotation, and which has, on at least one surface thereof, at least two series of lugs which project from the at least one surface, wherein the lugs are inserted into the longitudinal outer groove of the first member and the longitudinal outer groove of the second member, respectively.