An active compensation device to reduce chatter of a processing product and to compensate displacement due to thermal deformation of the processing product, comprising: a body in which a receiving space is formed; an MR actuator provided in an inner side of the receiving space and of which a damping force is changed according to change in viscosity of an MR fluid; and a magnetostrictive actuator provided in an outer side of the receiving space and including a magnetostrictive element of which length displacement occurs due to a magnetic force, characterized in that the MR actuator comprises: a first bobbin portion where a fluid space filled with the MR fluid is formed, and around which a first coil that generates a magnetic field is wound to change viscosity of the MR fluid; and an MR shaft fitted to be reciprocally movable in an axis direction in the first bobbin portion and of which a damping force is changed due to viscosity variation of the MR fluid; in that the magnetostrictive actuator comprises a second bobbin portion where the first bobbin portion is received and around which a second coil that forms a magnetic field is externally wound to change displacement of the magnetostrictive element, and in that the magnetostrictive element is provided between the first bobbin portion and the second bobbin portion such that displacement is generated in a vertical direction by the magnetic field of the second coil. a body in which a receiving space is formed; an MR actuator provided in an inner side of the receiving space and of which a damping force is changed according to change in viscosity of an MR fluid; and a magnetostrictive actuator provided in an outer side of the receiving space and including a magnetostrictive element of which length displacement occurs due to a magnetic force, characterized in that the MR actuator comprises: a first bobbin portion where a fluid space filled with the MR fluid is formed, and around which a first coil that generates a magnetic field is wound to change viscosity of the MR fluid; and an MR shaft fitted to be reciprocally movable in an axis direction in the first bobbin portion and of which a damping force is changed due to viscosity variation of the MR fluid; in that the magnetostrictive actuator comprises a second bobbin portion where the first bobbin portion is received and around which a second coil that forms a magnetic field is externally wound to change displacement of the magnetostrictive element, and in that the magnetostrictive element is provided between the first bobbin portion and the second bobbin portion such that displacement is generated in a vertical direction by the magnetic field of the second coil. a first bobbin portion where a fluid space filled with the MR fluid is formed, and around which a first coil that generates a magnetic field is wound to change viscosity of the MR fluid; and an MR shaft fitted to be reciprocally movable in an axis direction in the first bobbin portion and of which a damping force is changed due to viscosity variation of the MR fluid; in that the magnetostrictive actuator comprises a second bobbin portion where the first bobbin portion is received and around which a second coil that forms a magnetic field is externally wound to change displacement of the magnetostrictive element, and in that the magnetostrictive element is provided between the first bobbin portion and the second bobbin portion such that displacement is generated in a vertical direction by the magnetic field of the second coil.