This study explores the patterns and characteristics of job mobility among Korean youth through sequential analysis. It verifies initial career formation patterns to identify important implications in developing policies for effective labor market performance, using 15 years of job history data from the Korean Labor & Income Panel of the Korea Labor Institute. It finds that, first, simple laborers and service workers had the highest job mobility. Namely, young individuals begin their careers in jobs with low initial entry barriers and seek to change jobs quickly. Second, a significance test on job mobility showed that the mutual movement rate between jobs in professional, semi-professional, clerical and technical, machine operations-related, and simple labor fields was extremely low, indicating the presence of job mobility barriers. Third, females choose stable and familiar jobs compared to men, tending to adjust to one job type instead of considering new ones.