Abstract: A pendulum torsional-vibration reducing device includes: a rotor having a plurality of through-holes formed in the rotor with predetermined intervals in a circumferential direction of the rotor; a rolling element disposed in the through-holes so as to carry out pendular movement; and a casing fixed to the rotor so as to cover the rolling element, wherein the casing includes fixing pieces in tight contact with both side surfaces of the rotor so as to hold the rotor therebetween, and a thickness of the rotor at a position where the fixing pieces are in tight contact is thinner than a thickness of the rotor at a position where a rolling surface to which the rolling element is pushed by centrifugal force is formed.