A 69-year-old man with rheumatoid arthritis was referred to our department for further evaluation in October 2013. Bronchoscopy was performed, which did not lead to a definitive diagnosis. Subsequently, he developed a fever with worsening pulmonary infiltrates on chest radiography and computed tomography (CT). He was admitted to our hospital because post-bronchoscope pneumonia was suspected. CT-guided lung biopsy was performed after the pneumonia improved, which led to the diagnosis of pulmonary nocardiosis. Although he was treated with sulfamethoxazole/trimethoprim (ST), he died soon after. Serum β-D-glucan levels were elevated before treatment for pulmonary nocardiosis began; therefore, CT, magnetic resonance imaging, cardiac and abdominal ultrasonography, and fundoscopy were performed in addition to a blood culture. However, there were no findings suggestive of invasive fungal infection. It is possible that nocardiosis may cause elevated serum β-D-glucan levels.