Disseminated carcinomatosis of the bone marrow derived from solid cancer has a very poor prognosis, with disseminated intravascular coagulation(DIC). A 72-year-old man was admitted to our hospital after detection of a tumor in the pancreatic tail by CT imaging. Several images revealed that he suffered from cancer of the tail of the pancreas with multiple liver and bone metastases. Endoscopic ultra-sonography-guided fine needle aspiration detected adenocarcinoma cells from the tumor of the pancreatic tail. We also performed bone marrow aspiration, which confirmed adenocarcinoma cells in the bone marrow. We started to administer 1,000 mg/m2 of gemcitabine weekly. Laboratory data revealed that thrombocytopenia had occurred, and it developed into DIC after the first the administration of gemcitabine. In spite of the DIC state with thrombocytopenia, we were able to provide anticancer treatment using combination gemcitabine and S-1. He recovered from his DIC state, and the primary tumor was shrunk with a decrease of tumor markers after 2 courses of combination chemotherapy. Chemotherapy might be required for disseminated carcinomatosis of the bone marrow in order to promote tumor shrinkage and to prolonged expected survival, even if DIC was developed.