A plate (3, 35) gas burner (1) for boilers comprises a plurality of plates (3, 35) arranged parallel to each other and defining a burner body (2), a gas manifold (6) being situated at one first end (5) of the burner body (2) and presenting a plurality of nozzles (15) placed in correspondence with openings (13) cut in the individual corresponding plates (3, 3F), at a second end (7) opposed to the first one (5) a diffuser (8) being arranged where a flame is generated thanks to the combustion of the gas coming from the plates (3, 3F), the latter being crossed by a water duct (43). In correspondence with opposed sides (26, 27) of the burner body (2) are present support elements (25) suitable for directly co-operating with corresponding nozzles (15) of the gas manifold (6) so as to support the latter, such co-operation binding said manifold (6) to the burner body (2).