Automatic return hinge for fire doors adapted to be mounted on a wall within a jamb frame on which a leaf of such door is provided, such hinge comprising a frame-side portion and a door-side portion, the frame-side portion being U-shaped comprising a first fixing plate, which is fixed to the door case that extends in a pair of side tubular elements, the door-side portion comprising a second fixing plate, which is fixed to the door itself and rotates therewith, that extends in a central tubular element, the side tubular elements and the central one being, once the hinge is assembled, aligned with each other to form altogether an overall tubular element inside which both an automatic door re-closing device, and a device for inverting the force of the door re-closing movement are positioned, which cooperate with each other to generate a controlled movement of automatic re-closing, controlling the rotation movement of the central tubular element and of the second door fixing plate accordingly, wherein the re-closing controlled movement for a first angular range is obtained due to the contribution of a torsion spring of the automatic re-closing device contrasted by the contribution of the force inverter device, while for a second angular range until the closing of the door, due to the sum of the contribution of such torsion spring of the re-closing device and the contribution of a further spring of the force inverter device, accelerating the automatic closing movement of the door in the last section thereof, wherein such automatic re-closing device comprises, inside one of the two side tubular elements, a fixing body provided with a boring in which a first termination of the re-closing spring is inserted, at the second end of such re-closing spring the force inverter device is present, which device comprises a substantially cylindrical cam body provided with a boring in which such second termination of the spring is inserted, the cam body is arranged in the overall tubular element so as to be covered by the central tubular element, which also covers the re-closing spring, such cam body being integral with said central tubular element which rotates due to the opening or closing movement of the door, wherein the cam body has a side hole on its side surface, a slot obtained on the central tubular element allows the connection, for example by means of a screw which is inserted in such slot and which is screwed in the side hole, between such cam body body and the central tubular element, wherein such fixing body is made integral with the side tubular element by means of a dowel threaded in a cross hole obtained on such tubular element, wherein such automatic re-closing device is provided with means for adjusting the torsion of such spring, characterized in that the means for adjusting comprises a plurality of planar facets obtained on such fixing body so has to have a polygonal cross section, the dowel presses on the facets when screwed in the tubular element, blocking the possible rotation movement of the fixing body, the number of facets determines a corresponding number of spring force adjustment positions, and that the surface of the cam body opposite the one provided with the boring has a wavy profile and comprises four concave portions that are connected to each other, two balls are housed in two opposite such concave portions, such balls being inserted in seats obtained on the surface of a closed base of a cylindrical body integral with the internally hollow tubular element having a through hole on such base and inside which the compression spring is inserted.