Congenital right ventricular diverticulum is extremely rare and is associated with other congenital cardiac anomalies. It functionally behaves like an accessory ventricular chamber which contracts synchronously with the normal ventricles. Only dozens of patients with right ventricular diverticulum have been reported in literature worldwide and one case in Korea. An apical right ventricular diverticulum occurs in patients with thoracoabdominal midline defects or abnormalities of the cardiac position. However, an antero-superior diverticulum is usually associated with other congenital cardiac defects, such as a ventricular septal defect, tetralogy of Fallot, double outlet right ventricle, and pulmonary stenosis. We report a 69-year-old woman with a congenital right ventricular diverticulum without associated cardiac anomalies. The right ventricular diverticulum was diagnosed by echocardiography, right ventriculography, and cardiac MRI.