A screeding machine for leveling floor bases comprising a frame or chassis (BB), to which means (AA) for supporting and moving the machine frame (BB) in at least two directions and means (CC) for supporting and moving a milling device (DD) are associated; the milling device (DD) has, as a terminal element, a rotary tool (EE) for leveling and smoothing a substrate screed to obtain a finished surface on which to lay the floor. In particular, the support and moving means (CC) of the milling device (DD) include at least one articulated arm (CC), able to move the milling device (DD) along a straight line (GG) parallel to a further straight line (HH) joining two joints (J, K), which connect the articulated arm (CC) to the machine frame (BB), and in a direction which is substantially perpendicular to the moving direction of the machine frame (BB).