In this study, "Comfort Index" calculated from the heartbeat fluctuation was proposed in order to objectively evaluate the comfortableness on the swinging of active rocking chair. The heartbeat was used by reason that the heartbeat sensor does not almost get on examinee's nerves. Then, it was confirmed by the evaluation experiment that "Comfort Index" was effective for the relative evaluation in the identical examinee. Next, the swinging of the glider motion style active swing chair was evaluated using the proposed "Comfort Index". In the result, it was confirmed that the swinging was comfort. And the validity of "Comfort Index" was also confirmed from the result of simultaneously carried out questionnaire that the swinging is equivalently comfort with the active rocking chair.