There are only a few reports of cutaneous metastasis of breast cancer mimicking primary inflammatory breast cancer, and among them, seven cases originated from gastric cancer. Herein, we report a rare case of cutaneous metastasis from gastric cancer mimicking primary inflammatory breast cancer. A 55-year-old woman was referred for an erythematous patch with swelling on the left breast for 2 months. Fourteen years previously, she was diagnosed with advanced gastric cancer and underwent distal gastrectomy. Relapse of gastric cancer was diagnosed by peritoneal biopsy two years prior to presentation at our department, and when she was referred to our department, tumor was found to be disseminated in the pleural fluid and peritoneum confirmed by peritoneal biopsy and pleural fluid cytology. Ultrasonography, chest computed tomography, and mammography of the left breast showed no definite mass or microcalcification. Histopathological findings showed poorly differentiated carcinoma with prominent lymphovascular invasion. Immunohistochemical examination showed that the cells were positive for CEA and CK-7 but negative for CK-20, GCDFP-15, ER and PR. Radiation therapy was done in Lt. breast, and swelling and erythema were improved.