In this study, an electric swinging crib was designed to calm crying babies by giving them comfortable swinging stimuli. In addition, the authors examined and verified the usefulness of the designed crib comparing with an existing type of electric baby rack. To test our design, an experiment was carried out with 6 two month old babies at Kyushu University. In the experiment, after crying continuously for 30 seconds, the 6 babies were exposed to two different cases of swinging stimuli, as well as ‘no stimuli’ case for 4 minutes. The two cases of swinging stimuli were as follows; ‘Swing I’ (the swing by the proposed crib), and ‘Swing A’ (the swing by an existing baby rack). Babies calming responses were assessed with both behavioral and physiological indices. Regarding behavioral indices, the results showed that both ‘Swing I’ and ‘Swing A’ were effective to calm babies’ down. As for physiological indices, we analyzed the result of each baby’s heart rate and found out a possibility that ‘Swing I’ is more effective than ‘Swing A’. Furthermore, a declaration result by each baby’s mother also showed the possibility that ‘Swing I’ is more effective than ‘Swing A’.