Objectives: Occupational low back pain is a major cause of morbidity and the increases of medical and industrial costs. Efforts to control occupational low back pain have been largely unsuccessful, and further understanding of the risks including the psychological factors is needed. This retrospective study was designed to identify the effect of job stress on occupational low back pain among shipyard workers. Methods: The study group consisted of 976 male workers who were working at a Korean shipyard. A structured self-reported questionnaire was used to assess the participants’ physical work factors, job stress and general characteristics. Job stress was measured using Karasek’s JCQ(Job Content Questionnaire). Occupational low back pain was identified according to the NIOSH symptom survey criteria. Physical work factors were assessed using the Quick Exposure Check. Since the work duration can affect the relationship of physical work factors and job stress to occupational low back pain, we analyzed this association by dividing workers into two groups by work duration: 1) all workers, and 2) less than 5 years. Cox’s proportional hazard model was used to elucidate the relationship of job stress with occupational low back pain in these two groups. Data were analysed with SAS 8.1. Results: In the all workers group, job demand, bending or twisting of the back, and carrying heavy materials were associated with an increased the risk of occupational low back pain. In the workers with less than 5 years work experience, people with high job demand were more likely to experience occupational low back pain than those with low job demand. Conclusions: These results suggest that job stress as well as physical work factors can raise the risk of occupational low back pain. Especially, in the workers with less than 5 years work duration, job stress played a more crucial effect on the occurrence of occupational low back pain than physical work factors did.