The patient was a 27-year-old man with pulmonary tuberculosis, who was initially treated with isoniazid, rifampicin, ethambutol, and pyrazinamide. However, because of hepatic dysfunction and visual impairment, the four-drug therapy was switched to a three-drug regimen with isoniazid, rifampicin, and levofloxacin. At 9 weeks after the initiation of levofloxacin, the patient developed cervical lymphadenopathy, fever, systemic erythema, and hepatic dysfunction. He was diagnosed with drug-induced hypersensitivity syndrome (DIHS) based on positive results in the human herpesvirus (HHV)-6 DNA test, an indicator of HHV-6 reactivation. The symptoms improved after withdrawal of the antituberculosis drugs and initiation of steroid administration. However, considering the risk of relapse of DIHS, the tuberculosis treatment, which was initially planned for 9 months, was stopped at 7 months. Neither DIHS nor tuberculosis recurred.