A-72-year-old woman with an umbilical tumor was admitted to our hospital for resection of the tumor and to establish a definitive diagnosis. During the operation, we found an elastic mass near the pylorus. Pathological examination revealed the tumor as signet ring cell carcinoma, and endscopic examination and findings from biopsy of the stomach revealed that the tumor was caused by metastasis of the gastric cancer. Umbilical metastasis of the intraabdominal malignant neoplasm is known as “Sister Mary Joseph's nodule.” Early pathological examination should be performed to treat a patient with an umbilical tumor of unknown origin.