A railing device for securing working and/or standing areas to prevent people from falling, which railing device contains a railing bar, which extends in the direction of its railing bar longitudinal axis and has at least two railing bar ends (26.1, 26.1.1, 26.1.2, 26.2, 26.3, 26.4), which extend away from one another in opposite directions, wherein one railing bar end (26.1, 26.1.1, 26.2, 26.3, 26.4) of the railing bar ends (26.1, 26.1.1, 26.1.2, 26.2, 26.3, 26.4) has a slide-on and hook-in slot (27.1, 27.1.1, 27.2, 27.3, 27.4) for sliding the railing bar end (26.1, 26.1.1, 26.2, 26.3, 26.4) onto a support element (54; 54.1, 54.1.1, 54.1.2, 54.2, 54.2.1, 54.2.2, 54.3, 54.3.1, 54.3.2) of a railing fastening device (50.1, 50.1.1, 50.1.2, 50.2, 50.2.1, 50.2.2, 50.3, 50.3.1, 50.3.2) of a scaffolding brace or a scaffolding pole (51.1, 51.1.1, 51.1.2, 51.2, 51.2.1, 51.2.2, 51.3, 51.3.1, 51.3.2) and for detachably hooking the railing bar end (26.1, 26.1.1, 26.1.2; 26.2, 26.3, 26.4) onto the support element (54; 54.1, 54.1.1, 54.1.2, 54.2, 54.2.1, 54.2.2, 54.3, 54.3.1, 54.3.2) or into the support element (54; 54.1, 54.1.1, 54.1.2, 54.2, 54.2.1, 54.2.2, 54.3, 54.3.1, 54.3.2), and wherein the slide-on and hook-in slot (27.1, 27.1.1, 27.2, 27.3, 27.4) contains a support element receiving space (34.1, 34.1.1, 34.1.2, 34.2, 34.3, 34.4) for receiving a support element part (60, 60.1.1, 60.1.2, 60.2.1, 60.2.2, 60.3.1, 60.3.2) of the support element (54; 54.1, 54.1.1, 54.1.2, 54.2, 54.2.1, 54.2.2, 54.3, 54.3.1, 54.3.2) of the railing fastening device (50.1, 50.1.1, 50.1.2, 50.2, 50.2.1, 50.2.2, 50.3, 50.3.1, 50.3.2), and wherein the slide-on and hook-in slot (27.1, 27.1.1, 27.2, 27.3, 27.4), as viewed in a transverse direction perpendicular to the railing bar longitudinal axis, is outwardly open towards side faces (28.1.1, 28.1.2, 28.2.2, 28.2.2) of the railing bar end (26.1; 26.1.1, 26.2, 26.3, 26.4), which extend away from one another, and is also outwardly open in a first direction transverse or perpendicular to the transverse direction, and wherein the railing bar end (26.1, 26.1.1, 26.2, 26.3, 26.4) is designed such that the railing bar can be mounted as an advanced railing, for which the railing bar can be pivoted from a vertical or oblique intermediate position (62.2, 62.3) into a horizontal installation position (43.1, 43.2, 43.3, 43.4), and wherein the slide-on and hook-in slot (27.1, 27.1.1, 27.2, 27.3, 27.4) has a first slot part (37.1.1, 37.1.2, 37.1.3, 37.1.4), a first transition slot part (38.1.1, 38.1.2, 38.1.3, 38.1.4), and a second slot part (37.1.2, 37.2.2, 37.3.2, 37.4.2), wherein the first slot part (37.1.1, 37.1.2, 37.1.3, 37.1.4), which extends in a first slot part direction (39.1.1, 39.2.1, 39.3.1, 39.4.1), is outwardly open in the first direction and merges via the first transition slot part (38.1.1, 38.1.2, 38.1.3, 38.1.4) into the second slot part (37.1.2, 37.2.2, 37.3.2, 37.4.2), which extends away from the first slot part (37.1.1, 37.1.2, 37.1.3, 37.1.4) in a second slot part direction (40.1.2, 40.2.2, 40.3.2, 40.4.2), which forms an angle (42.1, 42.2, 42.3, 42.4) of greater than or equal to 45 degrees or greater than or equal to 60 degrees or greater than or equal to 90 degrees with the first slot part direction (39.1.1, 39.2.1, 39.3.1, 39.4.1), and wherein the first slot part (37.1.1, 37.1.2, 37.1.3, 37.1.4), viewed in a horizontal installation position (43.1, 43.2, 43.3, 43.4) of the railing bar, either is downwardly open at its lower slot part end or is upwardly open at its upper slot part end, and wherein either the downwardly open first slot part (37.1.1, 37.2.1) merges at its upper slot part end into the first transition slot part (38.1.1, 38.2.1), which merges into the second slot part (37.1.2, 37.2.2), which extends away from the other railing bar end (26.1.2) or forwards in the second slot part direction (40.1.2, 40.2.2) or the upwardly open first slot part (37.3.1) merges at its lower slot part end into the first transition slot part (38.3.1), which merges into the second slot part (37.3.2), which extends away from the other railing bar end (26.1.2) or forwards in the second slot part direction (40.3.2), characterised in that the second slot part (37.1.2, 37.3.2) merges upwards via a second transition slot part (38.2.2, 38.3.2) into a third slot part (37.2.3, 37.3.3), which extends upwards away from the second slot part (37.1.2, 37.3.2) in a third slot part direction (41.2.3, 41.3.3), which forms an angle (42.2, 42.3) of greater than or equal to 45 degrees or greater than or equal to 60 degrees or greater than or equal to 90 degrees with the second slot part direction (40.2.2, 40.3.2) and/or runs in parallel with the first direction and/or with the first slot part direction (39.2.1, 39.3.1).