This study aims to determine the effect of job satisfaction, work environment and organizational commitment on organizational citizenship behavior of PT. KAI DAOP V Purwokerto. This research uses quantitative methods. The population in this study were permanent office employees totaling 134, Sampling in this research is using nonprobability sampling method with purposive sampling technique where sampling is done with certain criteria. The results of the data obtained from the distribution of questionnaires were 101 respondents. Data analysis used multiple linear analysis. Based on the test results, the results obtained are: (1) Job Satisfaction, Work Environment and Organizational Commitment simultaneously affect Organizational Citizenship Behavior. (2) Partial test results show that Job Satisfaction has no significant effect on Organizational Citizenship Behavior, Work Environment and Organizational Commitment have a significant positive effect on Organizational Citizenship Behavior.