A lit-up marking device for floors includes a section with a generally U-shaped layout defined by a flat base and by two end wings. Intermediate inlets for the pressure-fitting of a translucent protector are at the flat base. Lighting is positioned on a longitudinal support housed in the section and a translucent protector has a central portion and two side feet forming an arrow-head for fitting into the section. The wings of the section have, on their interior end, respective concavities which face concavities formed on the exterior in the initial zone of the side legs of the translucent protector. The cavities form one cavity with an opening for inserting optional elements for fixing the translucent protector onto the section.