BACKGROUND: With the development of technology, extensive use of computers in the workplace is prevalent and increases efficiency. However, computer users are facing new harmful working conditions with high workloads and longer hours. This study aimed to investigate the association between computer use at work and self-reported depressive and anxiety disorder (DAD) in a nationally representative sample of South Korean workers. METHODS: This cross-sectional study was based on the third Korean Working Conditions Survey (2011), and 48,850 workers were analyzed. Information about computer use and DAD was obtained from a self-administered questionnaire. We investigated the relation between computer use at work and DAD using logistic regression. RESULTS: The 12-month prevalence of DAD in computer-using workers was 1.46 %. After adjustment for socio-demographic factors, the odds ratio for DAD was higher in workers using computers more than 75 % of their workday (OR 1.69, 95 % CI 1.30-2.20) than in workers using computers less than 50 % of their shift. After stratifying by working hours, computer use for over 75 % of the work time was significantly associated with increased odds of DAD in 20-39, 41-50, 51-60, and over 60 working hours per week. After stratifying by occupation, education, and job status, computer use for more than 75 % of the work time was related with higher odds of DAD in sales and service workers, those with high school and college education, and those who were self-employed and employers. CONCLUSIONS: A high proportion of computer use at work may be associated with depressive and anxiety disorder. This finding suggests the necessity of a work guideline to help the workers suffering from high computer use at work.