To prevent the disengagement of a weight of a dynamic damper arranged in an inner space of a torsion beam of a suspension without adapting a special disengagement prevention member.

A dynamic damper 32 arranged inside a torsion beam 20 having a U-shape section and provided with an opening 204 comprises a support member 37 supporting a weight 35 via an elastic leg 36 so as to be capable of vibrating. The support member 37 comprises: a weight support part 371 arranged so as to cover the opening 204 of the torsion beam 20 and supporting the weight 35; and a pair of weight disengagement prevention part 373 extending toward an inside of the torsion beam 20 from both right and left ends of the weight supporting part 371 and faces both the right and left ends of the weight 35. When the elastic leg 36 is broken and the weight 35 is separated, the weight 35 is held in a space surrounded with an inner surface of the torsion beam 20, the weight supporting part 371 and the pair of weight disengagement prevention part 373.