In the previous papers, the authors proposed methods for analyzing and evaluating the psychological effects on motion-sickness, using the fuzzy theories. Another important factor for analyzing and evaluating the motion-sickness incidence is the physiological phenomena arose in the human bodies on board ships and other vehicles. It has been considered difficult, however, to measure and analyze the physiological phenomena such as electroencephalogram (EEG) and electrocardiogram (ECG) under whole-body exposure to low-frequency oscillations, from the viewpoints of medical science. The authors carried out the measurements of EEG and ECG of subjects exposed very low-frequency oscillation using a ship-motion simulator. They also tried to analyze the measured EEG and ECG by means of spectral analysis, wavelet analysis and other techniques. In the present paper, they show the method for measuring physiological phenomena arose in the subjects brain and heart and also show the method of analyses using spectral analysis and wavelet analysis techniques. Some results which clearly explain the motion-sickness incidence physiologically are shown.