Absence of long head of biceps tendon is a very rare anomaly. We encountered a 19 year-old male patient who had right shoulder subluxation. On magnetic resonance imaging, shallow intertubercular groove on right humerus was observed, and absence of long head of biceps tendon was discovered. Arthroscopically, labral rupture and absence of long head of biceps tendon were also evident. Left shoulder had a similar symptom as right 5 months after the initial development of the symptom on the right shoulder. Both MRI and arthroscopy revealed absence of long head of biceps tendon and labral ruptre. Arthroscopic labral repair was performed for both shoulders, and, postoperatively, they were fixated with abduction brace. In this case, it is considered that the absence of long head of biceps tendon triggered the instability of shoulder found in our patient.