An energy regeneration device of a suspension system for a vehicle is provided and includes a suspension link connecting a wheel carrier to a vehicle body and a bush unit disposed between a vehicle body connection portion of the suspension link and the vehicle body, outputs hinge motion of the suspension link via an output gear. A rotation fixing mechanism rotates the output gear by connecting the output gear to a side of the suspension link. A one-way power transmission mechanism connected with the output gear receives the hinge motion via an input gear and outputs one-way rotational power. A generator generates electricity while being rotated by the transmitted one-way rotational power. A speed-up mechanism disposed between the generator and the one-way power transmission mechanism transmits the one-way rotational power to the generator. A rectifier electrically connected with the generator, rectifies the electricity generated by the generator.