A medicament for improving prognostic survival in therapy of malignant tumor is provided that may improve prognostic survival in DIC patients where the basal disease is malignant tumor, especially malignant tumor in hematopoietic organs. The medicament according to the invention comprises as a main active ingredient Activated Protein C, which is obtained from plasma or prepared by using the genetic recombination technique, and efficiently prolongs life-span of DIC patients where the basal disease is malignant tumor, especially malignant tumor in hematopoietic organs. In particular, the medicament may reduce adverse side effects of chemotherapeutics in chemotherapy of malignant tumor to enhance efficacy of said therapy and improve prognostic survival of patients suffering from malignant tumor.