An hinge device with fulcrum at variable position for a door (2) of a structure (3) is provided with connecting members, first (4) and second (5), mutually connected and respectively fit to be fixed to the door (2) and to the structure (3) for rotating the door between the extreme closing (C) and the extreme opening (A) in which the door (2), in an operating condition of the structure, is respectively almost vertical and approximately horizontally orientated.The second connecting member (5) has a first fixed pivot (6) and a second fixed pivot (7) for the rotating connection respectively with a first balancing mean (8) and a second balancing mean (9) mutually bound.The end opposite to the first fixed pivot (6) of the first balancing mean (8) is connected by means of a first mobile pivot (10) to an end of the first arm mean (11) having the remaining end connected to the first connecting member (4) by means of a second mobile pivot (12).The end opposite to the second fixed pivot (7) of the second balancing means (9) is connected by means of a third mobile pivot (13) to the first connecting member (4).