A 28-year-old rheumatoid arthritis woman treated with adalimumab was admitted with fever, cough, and right chest pain. X-ray showed right pleural effusion. By medical thoracoscopy, diffuse white nodules were observed, and biopsy specimen demonstrated epithelioid cell granulomas with necrosis and auramine-stained organisms, which suggested a diagnosis of tuberculous pleurisy. Medical thoracoscopy can be a potent diagnostic method when tuberculous pleurisy is suspected. Notably, despite latent tuberculosis treatment, active tuberculosis was not prevented.