An anti-extraction safety device having, for each roller (13, 14), a rotationally fixed, preferably enveloping, shroud element (32, 33) forming a single-component functional mechanical set with its counterpart. The shroud parts are inclined and each has an extension (46, 47), at the base, which extends beneath the projecting flanks (21, 22) of the head of the guiding rail (19) to prevent extraction of the guidance set. At the front, the base of the shroud parts is preferably moulded into a spout for collecting and disposing of objects which may be present on the guiding track. The anti-extraction safety device can be used for rail guidance of road vehicles used for public transport.