Abstract: In order to investigate the change of eye movement system of VDT operators,horizontal involuntary eye movement during fixation on a small target is measured by photo-electric recording of corneal reflection before and after 2-hours VDT work. Power spectrum of drift is estimated with the autoregressive model. Both the Amplitude and velocity of flick are obtained. For 2-hours VDT work, the significant decrease in the amplitude and velocity of flick, in the power of spectrum of drift is recognized as of l% more or less. Near point distance (NP) and subjective symptoms are also measured during VDT work. NP and subjective symptoms show the visual fatigue.The correlation between the increase of NP and the change of involuntary eye movement is recognized.It is concluded that the variation of involuntary eye movement can be applied to evaluate visual fatigue.