The prognosis for patients who experience hemostatic complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is poor. However, no report has investigated disseminated intravascular coagulation (DIC) caused by the complications of allo-HSCT without infection. Recombinant human soluble thrombomodulin (rhTM) was used to treat 12 episodes of DIC (n = 10; group 1) caused by allo-HSCT complications such as acute graft-versus-host disease (aGVHD) or thrombotic microangiopathy (TMA), and the clinical outcomes were compared with those of historical controls (n = 9; group 2) treated for DIC without rhTM. In group 1, the mean DIC score was significantly improved after using rhTM. Fibrinogen degeneration product (FDP), C-reactive protein (CRP), and the inflammatory cytokine high-mobility group box 1 (HMGB1) were also significantly decreased. Serial changes from the baseline values of platelet counts and levels of FDP were significantly better in group 1 than in group 2. The recovery rate from DIC was significantly higher in group 1 than in group 2. These findings suggest that rhTM is effective against both DIC and systemic inflammatory complications after allo-HSCT.