A paradoxical response in tuberculosis is defined as clinical and radiological worsening of previous lesions or development of new lesions after initial improvement during the process of anti-tuberculous treatment. The authors report on a patient who developed massive pleural effusion as a paradoxical response after 8 weeks of anti-tuberculous treatment. The patient’s symptoms were improved with thoracostomy without any change of anti-tuberculous medications. If symptoms worsen during the process of anti-tuberculous treatment, drug resistance, non-compliance, or other diseases should be excluded first. If it is regarded as a paradoxical response, the treatment plan need not be changed except for additional conservative treatment.