A shaking device comprises an engine (3) rotating a pinion (5) engaged to a first gear ring (7) of a first wheel (9) coaxially fixed to a crankshaft means (11) connected to a big end of a connecting rod (13) whose small end is connected to a pin (15) connecting said small end to a pole (17) having a hook means (49) and constrained to reciprocate along a sliding straight line (A) laying on the longitudinal axis of the pole (17) and crossing the rotation geometric axis (R) of the first wheel (9) and of the crankshaft means (11). The pinion (5) further engages a second gear ring (19), equal or symmetric to the first gear ring (7), of a second wheel (21) having the same rotation geometric axis of the first wheel (9) and facing the latter (9). Each first (9) and second (21) wheel has a respective first (23) and second (25) mass means positioned in a way that, when they rotate together with the respective wheels (9, 21), they cross each other approximately along the sliding straight line (A) and that their motion is in phase opposition with respect to the reciprocating of the pole (17). The first wheel (9) has a first rotation shaft (27) outward protruding and having a respective first bearing means (29) housed in a respective seat of a device (1) crankcase body (31). The crankshaft means (11) has a second rotation shaft (35) outward protruding and having a respective second bearing means (37) housed in a respective seat of the crankcase body (31). The crankshaft means (11) further has a connecting rod pin (39), for the big end of a connecting rod (13), having an end fixed to the first wheel (9). The second wheel (21) is connected in a freely revolving way to the second rotation shaft (35) by a third bearing means (41). The rotation geometric axis of the first (27) and second (37) rotation shaft, of the first (29), second (37) and third (41) bearing means and of the second wheel (21) coincide with the rotation geometric axis (R) of the first wheel (9) and of the crankshaft means (11). The longitudinal geometric axis of the connecting rod pin (39) is parallel and spaced out from the rotation geometric axis (R).