Device for controlling the sharpening state of a blade (2) having a cutting edge (20) delimited by two sides (21, 22) converging towards a plane (X) that contains the cutting edge itself. The device comprises two control surfaces each of which is in contact with a corresponding side (21, 22) of said cutting edge (20) and is connected with at least one transducer (R1, R2, R4), which produces an electrical displacement signal (S1, S2; S4) proportional to a displacement of the control surface with respect to said plane (X). Furthermore, the device comprises a processing unit (E) that receives said displacement signals (S1, S2, S4) and compares them, emitting an error signal if the comparison produces a value that exceeds a predetermined limit. The processing unit is connected to means (101, 102) for supporting and moving sharpening means (100).