The invention relates to a boarding aid (20) for a motor vehicle, in particular a sliding step of a door entry of a passenger transportation vehicle, said boarding aid being capable of being moved from an idle position into a usage position and back in a direction, which runs parallel to the side edges (28), and encompassing a planar element (22), a front side, two side edges (28), and a rear side. The planar element (22), on its side edges (28), encompasses barriers (30), which can be moved from a first upright position, in which they extend upwards in relation to a stepping surface of the planar element (22), into a second lowered position and vice versa, wherein the movement of the barriers (30 is effected by moving the planar element (22).
