The purpose of this study is to evaluate the performance of a new flicker tester ("AQ Flicker": High Accurate and Quick Flicker Tester) through the field-test for truck drivers and office workers. The AQ Flicker has been developed to eliminate subject's arbitrariness and deceptiveness using multiple LEDs which are flickered by program control. In the field the fatigue of the participants before and after work has been evaluated using the AQ Flicker. Furthermore, subjective fatigue feelings, reaction time, body sway, salivary alpha-amylase activity, and heartrate R-R interval have been measured. In the result the flicker values of AQ Flicker were well correlated with mental fatigue and muscle fatigue surmised from the psychological, physical, and physiological measures described above.