A rounding machine of portions (10) of dough mixture, in particular in the food sector, comprises: a bearing frame (11); a main plate (20) which supports, on a lower face thereof, a plurality of forming elements (21), each of which is particularly suitable for engaging a respective portion of dough mixture; a central support (30), mounted on the bearing frame (11) and connected to the main plate (20), the central support (30) being configured to move the main plate (20) according to an eccentric trajectory about a first stationary axis (X) and rotatably connected to the central plate (20) idle about a second axis (Y) of rotation parallel to the first axis (X); an anti-rotation mechanism (50) configured to prevent a rotation of the main plate (20), constraining the main plate (20) to a translation movement along the eccentric trajectory about the first axis (X). The rounding machine (10) is characterised in that the anti-rotation mechanism (50) is interposed between the bearing frame (11) and the main plate (
