The invention relates to a cleaning apparatus (10) for functionally regenerating a brush (20) which can be used for washing a flexographic plate; in particular, the apparatus is configured to regenerate a brush (20) comprising a cylindrical core (5) about which a channel (4) supporting filaments (3) is fixed according to a spiral shape. The apparatus comprises a frame defining a rotation axis (100) for the brush and a motorized assembly, which can be operatively connected to an end of said cylindrical core (5) of the brush (20) to rotate it about the rotation axis (100). The apparatus (10) further comprises a cleaning unit (30) comprising a carriage (31), movable along a rectilinear guide (32) and a tool (33) provided with an end (33A) adapted to penetrate into the spaces defined between the turns of the spiral to detach the polymer and monomer residues hardened in said spaces as a result of the use of said brush for said washing.