A 57-year-old man presented with shortness of breath and ankle edema. Constrictive pericarditis with an unexplained mass surrounding the heart was diagnosed by ultrasound. Accordingly, F-FDG PET/CT was performed. Multiple PET-positive noduli and irregular tissue were located in the pericardium, with pleural fluid present, but without additional pulmonic or pleural pathology. A pericardiectomy was successfully performed. Histopathology and immunohistochemical staining revealed epithelioid mesothelioma.