A new torsional dynamic vibration absorber is proposed, consisting of a circular conducting plate and four cylindrical rare-earth magnets of which magnetic energy is extremely strong, and its absorbing characteristics is investigated experimentally and theoretically. First, the magnetic torsional stiffness between two magnets is analyzed theoretically, and the magnetic damping characteristics by the relative motion between the magnets and the conductor is investigated experimentally. Second, a solution of the steady-state vibration response is derived from the equation of motion with the term of the nonlinear magnetic torsional force, and the criterion of its stability is obtained. Subsequently, the experimental results about the optimum absorbing effect are presented.