A pulley device for a tensioner roller or winding roller of a transmission element, providing a pulley, and a bearing. The bearing includes a rotating outer ring mounted to the pulley, a fixed inner ring, and at least one row of rolling elements arranged between the rings. The inner ring of the bearing has at least one end portion protruding axially with respect to the outer ring. The pulley is provided with at least one pulley element that is C-shaped in axial section. One of the at least one pulley elements is provided with a lateral portion extending substantially radially to pass into the immediate vicinity of an outer surface of the axially protruding end portion of the inner ring.