A balancing device for a rotating part , - said rotating part defining a rotation axis , - said balancing device defining a central axis and being able to be bound to said rotating part so that said central axis basically coincides with said rotation axis , and comprising: - at least one eccentric mass that can be rotated about said central axis and that is not balanced in relation to said central axis , - at least one balancing motor , designed to rotate said eccentric mass , in relation to said rotating part around said central axis , - a fixed portion , which is integral, in use, with said rotating part , and being characterised in that said balancing motor comprises piezoelectric type motor means, - said balancing motor comprising at least one active portion , which is movable in relation to said fixed portion and connected to said fixed portion by at least one piezoelectric element , said piezoelectric element being designed to move, by its active deformation following electrical impulses, at least part of said active portion in the circumferential direction in relation to said central axis , - wherein said active portion comprising a support , protruding in the direction of said central axis , and said support resting, in the direction of said central axis , on said eccentric mass , - and said balancing device comprises axial thrust means designed to press said support against said eccentric mass . - said rotating part defining a rotation axis , - said balancing device defining a central axis and being able to be bound to said rotating part so that said central axis basically coincides with said rotation axis , and comprising: - at least one eccentric mass that can be rotated about said central axis and that is not balanced in relation to said central axis , - at least one balancing motor , designed to rotate said eccentric mass , in relation to said rotating part around said central axis , - a fixed portion , which is integral, in use, with said rotating part , and being characterised in that said balancing motor comprises piezoelectric type motor means, - at least one eccentric mass that can be rotated about said central axis and that is not balanced in relation to said central axis , - at least one balancing motor , designed to rotate said eccentric mass , in relation to said rotating part around said central axis , - a fixed portion , which is integral, in use, with said rotating part , and being characterised in that said balancing motor comprises piezoelectric type motor means, - said balancing motor comprising at least one active portion , which is movable in relation to said fixed portion and connected to said fixed portion by at least one piezoelectric element , said piezoelectric element being designed to move, by its active deformation following electrical impulses, at least part of said active portion in the circumferential direction in relation to said central axis , - wherein said active portion comprising a support , protruding in the direction of said central axis , and said support resting, in the direction of said central axis , on said eccentric mass , - and said balancing device comprises axial thrust means designed to press said support against said eccentric mass . <EOS>