The invention relates to an elevator car roof railing (1) with collapsible sides (13) hinged on a supporting frame (5) on the car roof (3), characterized in that it includes: two sides (13) that can be folded inwards as an accordion in at least two parts (15), perpendicular to the landing door opening (9) of the elevator shaft and hinged to said supporting frame (5) in their bottom part, an upper rear side bar (17) connected to the rear upper end of each of said folding lateral sides (13), an actuation handle (19) with a length approximately equal to the depth of the elevator car and hinged to said supporting frame (5) or close thereto, in the rear middle part thereof, perpendicular to said landing door opening (9) in the shaft, wherein this handle (19) is connected at least by a rod (35) hinged in the median plane to the upper rear side bar (17), and by a lateral rod with a terminal ball-and-socket joint to the rear part of each of the folding lateral sides (13), wherein said handle (19) can be lifted through the landing door opening (9) from a lower, substantially horizontal position in which the railing is collapsed, to a locked upper position that is substantially vertical, pulling along the two folding lateral sides (13) at the same time to erect them vertically and form the third rear side of the railing with the upper bar (17) on which it is applied and locked and with the rear connecting rods (35, 39) for said lateral sides (13), and inversely, can be lowered from the upper position to the lower position in which the displacement of the handle (19) causes the simultaneous folding of the two folding lateral sides (13) of the railing, and therefore the collapse of the railing itself to a small height above the car roof (3).