Abstract: The hereby presented invention concerns a rocking device that includes a drive mechanism which actuates with an alternative motion one end of an elastic cord, which, through its other end, impairs the alternative motion to a carrying handle or any other equivalent attachment point of a baby chair or support or carrying for youngsters (babies), that is adequate for that purpose, being the drive mechanism and the elastic cord associated in such a way that, by adjusting its motor idle speed, the frequency of the inducer movement adjusts itself to the natural frequency of the movement induced on the baby chair or support device with the baby. In an alternative version of the invention the rocking device is attached to the baby chair or support device and the elastic cord is fixed to an external attachment point.