A device for folding a web for producing absorbent sanitary articles along at least one longitudinal fold line parallel to its feed direction includes two diverting elements positioned on opposite sides of the web one after the other, to operate in succession on respective lateral portions of the web and allow transversal folding of one lateral portion on the other and both on the web. Each diverting element has a diverting surface which is used for folding and which is equipped with a plurality of holes to emit jets of air under pressure at a tangent to the diverting surface, directed transversely to the feed direction of the web along the same direction as the direction along which the two lateral portions are transversely folded by the diverting surface and defining between the latter and the web a laminar fluid bed.
