The authors have proposed a new physiological index ρmax which is the maximum cross-correlation coefficient between blood pressure and heart rate whose frequency components are limited to the Mayer wave-band (0.04-0.15Hz). The advantages of this index are small individual difference and high reproducibility compared with other physiological indices which are calculated independently single cardiovascular measurements. The previous study showed that the index ρmax is possible to assess visually-induced motion sickness. However, the relation between the proposed index and autonomic nervous activity has not been clarified yet. In this study, the change in ρmax during sympathetic or parasympatlietic blockage has been investigated in comparison with conventional indices in an animal experiment. The results have indicated that ρmax does not have information on parasympathetic nerve activity but sympathetic one.