In a vehicle seat device including a vibration system (18) formed from a seat back (3) and a headrest (4) being equipped with a dynamic damper (20), the dynamic damper (20) is formed from an elastic member (21) that is embedded within a cushion member (13) of the vibration system (18) and formed from a rubber or elastomer that is softer than the cushion member (13), and a weight (22) embedded in the elastic member (21). Thus it is possible to provide a vehicle seat device that includes a dynamic damper having a small number of components and a simple structure.