We report a case of gastric cancer that presented as transverse myelopathy due to spinal bone metastasis. A 45-year- old man with advanced gastric cancer underwent distal gastrectomy and lymph node dissection for curative intent. However, pathological examination of the specimen revealed positive cytological findings in the peritoneal lavage fluid in addition to serosal invasion and lymph node metastasis(pT4aN3bCY1, stage IV). Three months after the operation, during the second course of chemotherapy with S-1, he began to complain of back pain, and positron emission tomography-computed tomography revealed spinal bone metastasis. Despite immediate radiotherapy for the bone metastasis, he soon suffered from paraplegia in the lower extremities followed by disturbances of bladder and bowel function. We created a sigmoid colostomy, which enabled self-care for defecation, and resumed radiotherapy and chemotherapy. Bone metastasis of gastric cancer is rare but the prognosis is very poor. Because of a rapidly deteriorating clinical course, early diagnosis and multidisciplinary approaches are important for gastric cancer patients with spinal metastasis.