Objective: The purpose of this study was to investigate the effects of a task-oriented vocational rehabilitation program on the hand function and job competency and generalization for people with an intellectual disability. Methods: The study period was April 4 through June 24, 2016, and the subjects were four adults with an intellectual disability, who use the E welfare center in G. City. The study design was a multiple probe design across the behaviors of single subject research. The intervention was conducted in stages, i.e., basic competency, job competency, and the generalization process, for 50 min, two times a week, during a 12 week period. For the basic competency process, the grasping power, dexterity, and bilateral hand manipulation; for the job competency process, the number of finished strings and their accuracy; and for the generalization process, the number of finished bracelets, finishing time, and accuracy were all measured after the every session. Results: Their hand function and basic job performance were improved through the task-oriented vocational rehabilitation program. In addition, their job competency and generalization, which are required to hold and maintain a job, were improved through repetitive training of tasks conducted through a job analysis. Conclusion: The program worked effectively on the hand function, job competency, and generalization, all of which affect one's job performance. Therefore, this study proposes use of such a program for vocational rehabilitation.