Job demand is an important construct that brings negative impacts on librarians’ job outcome. Despite the effect of positive organizational constructs such as job characteristics, work engagement and organizational citizenship behavior, job demand remain a challenge. The study investigated the effect of positive organizational behavior on job demand among librarians in Nigeria. The study employed survey research design. The population of the study consisted of 624 librarians from 38 public universities in Southern Nigeria. Data were analyzed using descriptive and inferential statistics. The findings revealed that the joint combine effect of positive organization behavior such job characteristics (β=.001, p>.05), work engagement (β=
.112, p<.05) and organizational citizenship behavior (β=.214, p<.05) significantly influenced job demand among librarians in Nigeria. The study concluded that positive organizational behavior contribute to low level of job demand among librarians in Nigeria and library management should maintain good work practice to prevent job demand.