Purpose: To examine the relationship between working in a very dry clean room (relative humidity less than 1%) and dry eye, and its progress by lapse of time. Methods: Targeting 352 employees working in a clean room of onesecondary cell production plant, it performed a dry eye examination in 2011, 2012, and 2013, totally three times. It performed the TFBUT, Schirmer’s test,slit lamp microscope examination, and Mac Morning survey. dry eye stages were classified based on the DEWS criteria. The annual examination results were analyzed through the Anova test and the post-mortem was conducted with Tukey, and in order to learn the effect of working time on dry eye, anunivariate logistic regression analysis was conducted having dry eye examination results as a dependent variable and working time as an independent variable. Results: According to TFBUT and Mac Morning survey, dry eye degenerated as time passed. There was no change in the Schirmer’s test. Considering that as a result of the univariate logistic regression analysis having dry eye examination results as a dependent variable and working time as an independent variable, in the Mac Morning survey, the cross ratio increased up to 1.127(95%CI 1.033~1.230)by lapse of time, it could be found that as working time is elongated, the complaining rate of dry eye increases. Conclusion: It is thought that a clean room with a relative humidity less than 1% affects causing dry eye. Working time limitation, job rotation, and health care such as prescription of artificial tear solution without preserved agent are necessary.