The simulator sickness in immersive virtual environment was studied for future questionnaire improvement. The top four sickness scores are general discomfort, eyestrain, difficulty concentrating, and fatigue. These experimental results suggest future questionnaire for immersive virtual environment to concentrate on problems about eyes and seeing. Furthermore, the least four simulator sickness are burping, increase salivation, sweating, and stomach awareness. These sickness symptoms might be reduced to shorten future simulator sickness questionnaire.