Gastric antral vascular ectasia (GAVE) is an angiodysplastic disorder that causes gastric bleeding. GAVE can develop as a complication of hematopoietic stem cell transplantation (HSCT-GAVE), and it has been suggested that it may be associated with oral administration of busulfan. We report two cases of HSCT-GAVE after a conditioning regimen containing intra-venous busulfan (ivBu), not oral busulfan. The first case, a 42-year-old woman with blastic plasmacytoid dendritic cell neoplasm, underwent second allogeneic HSCT with conditioning regimen consisting of cyclophosphamide (120 mg/kg) and ivBu (12.8 mg/kg). HSCT-GAVE developed on day 84 post-transplant, and argon plasma coagulation (APC) was performed successfully. The second case, a 60-year-old woman with acute myelogenous leukemia, underwent allogeneic HSCT with the conditioning regimen consisting of ivBu (12.8 mg/kg) and fludarabine (150 mg/kg). She developed melena and was diagnosed with GAVE by endoscopy on day 145 post-transplant. Although complete hemostasis was not achieved despite four administrations of APCs, the melena spontaneously terminated on day 235 post-transplant. To our knowledge, this is the first report describing HSCT-GAVE after ivBU-based HSCT. Although there is no established therapy for HSCT-GAVE, APC may be an option for HSCT-GAVE.