While receiving appropriate treatment, patients with tuberculosis occasionally have unusual, paradoxical reactions, with transient worsening of lesions or the development of new lesions. This report is a case of tuberculosis brain abscess and tuberculosis peritonitis with intra-abdominal abscess that developed during appropriate anti-tuberculosis chemotherapy. A 45-year-old male patient had been diagnosed as with all-drug susceptible pulmonary tuberculosis with pleurisy. Subsequently, the patient underwent standard treatment with anti-tuberculosis therapy; the pulmonary lesions improved. Three months after initial treatment, the patient developed brain abscesses and peritonitis. With the addition of corticosteroid treatment, the patient's neurologic symptoms were relieved. Exploratory laparotomy with surgical drainage was performed and a diagnosis of tuberculosis peritonitis was confirmed on biopsy. Anti-tuberculosis therapy was continued for 19 months, the patient improved eventually without further complications, although the therapeutic regimen had not been altered. In this case, the paradoxical response to treatment may have been involved in the pathogenesis of disease.