Foot-rest structure for the driving side of the floor of a motor-vehicle, comprising: - a foot-rest support, secured to the floor panel of the motor-vehicle, - a covering element mounted on said foot-rest support, - a trim lateral panel having a front edge connected to said covering element, said foot-rest structure being characterized in that: - said foot-rest support is constituted by a three-dimensional body of plastic material, defining a three-dimensional volume projecting from the floor panel, adjacent to said trim lateral panel, and having a front inclined surface, an upper surface and at least one inner lateral surface facing towards the inside of the passanger compartment, - said covering element is constituted by a body of plastic material arranged over said foot-rest support, and having: - a front inclined wall covering said front inclined surface of the foot-rest support and defining a foot resting surface, - an upper wall and a lateral wall respectively arranged over said upper surface and said at least one inner lateral surface of said foot-rest support, - said covering element and said foot-rest support being provided with engagement elements and seats cooperating with said engagement elements, for their mutual rigid connection, - the front edge of the trim lateral panel is connected only to said covering element, with no direct connections to said foot-rest support, said covering element having said front inclined wall which, on a lateral edge thereof facing the trim lateral panel, forms a channel in which the front edge of the trim lateral panel is received, said front edge of the trim lateral panel and said channel having engagement elements and seats cooperating with said engagement elements, for rigidly connecting the trim lateral panel to said covering element. - a foot-rest support, secured to the floor panel of the motor-vehicle, - a covering element mounted on said foot-rest support, - a trim lateral panel having a front edge connected to said covering element, - said foot-rest support is constituted by a three-dimensional body of plastic material, defining a three-dimensional volume projecting from the floor panel, adjacent to said trim lateral panel, and having a front inclined surface, an upper surface and at least one inner lateral surface facing towards the inside of the passanger compartment, - said covering element is constituted by a body of plastic material arranged over said foot-rest support, and having: - a front inclined wall covering said front inclined surface of the foot-rest support and defining a foot resting surface, - an upper wall and a lateral wall respectively arranged over said upper surface and said at least one inner lateral surface of said foot-rest support, - said covering element and said foot-rest support being provided with engagement elements and seats cooperating with said engagement elements, for their mutual rigid connection, - the front edge of the trim lateral panel is connected only to said covering element, with no direct connections to said foot-rest support, said covering element having said front inclined wall which, on a lateral edge thereof facing the trim lateral panel, forms a channel in which the front edge of the trim lateral panel is received, said front edge of the trim lateral panel and said channel having engagement elements and seats cooperating with said engagement elements, for rigidly connecting the trim lateral panel to said covering element.