When suffering from seasickness onboard ships and other vehicles, the first symptom due to discomfort appears in the face as fine emotional changes. This facial expression may due about the measure of motion-sickness incidence by external appearance. The authors propose a mathematical model for analyses and evaluation of fine changes of facial expression and emotions. Methods developed in the field of fuzzy theory are introduced in modelling mathematically. Many sets of line-drawings of human face are produced in which eyebrows, eyes and mouth are parameterized and can be deformed. Face drawings are evaluated and classified into any of six emotions previously categorized. The evaluating experiments were carried out under cooperation of many university students. Methods of fuzzy measure and fuzzy integral are concluded to be very useful in analyzing and evaluating human emotions and facial expressions.