This study aims to determine the relationship between Big Five Personality with Organizational Citizenship Behavior (OCB). This research uses quantitative research method with correlational research type. Population in this research is Civil Servant Generation Y in Institution X. The participants in the study were 90 civil servants working in Institution X. Big Five Personality in this study was measured by Big Five Inventory (BFI) and Organizational Citizenship Behavior (OCB) was measured by Organizational Citizenship Behavior Scale (OCBS). Data analyzed by Pearson Product Moment correlation. The results of this study showed that there is positive and significant correlation between agreeableness with OCB, there is positive and significant correlation between conscientiousness with OCB, there is positive and significant correlation between openness to experience with OCB, whereas neuroticism showed negative and significant correlation with OCB, but extraversion did not showed significant correlation with OCB.