An intracapsular and pericapsular infection of the temporomandibular joint (TMJ) is rare. The invasion of bacteria into the joint space can occur through several routes. Among them, hematogenous spread is most common. This report describes three cases of abscess formation in the TMJ (intracapsular and pericapsular infection). The patients were treated with supportive care and surgical intervention (incision and drainage) under hospitalization, and their symptoms had improved. Pain of the TMJ is a typical symptom of temporomandibular joint disorders (TMD). On the other hand, an infection of the TMJ can also cause pain on the affected side, and can be misdiagnosed as routine TMD. Therefore, the possibility of an infection of the TMJ cavity should be considered when treating TMD.