The rewinding machine comprises: a first and a second lower winding roller (5, 7) defining a winding cradle for a reel (R) of web (N); a third upper roller (13) having a mobile axis (13) arranged over said first and second lower winding rollers and carried by two mobile slides (11) to allow for the increasing dimension of the reel under formation in said winding cradle. The two slides (11) carry two cylinders (21, 27) whose axes are parallel to the axis (13A) of the third upper roller (13) which are provided with a reciprocal approaching and distancing movement for either approaching or distancing the reel under formation in said cradle.