In 2018, two novel antibody therapies, inotuzumab ozogamicin (InO) and blinatumomab, against relapsed or refractory acute lymphoblastic leukemia were approved in Japan. In InO, the antitumor drug ozogamicin is conjugated to the anti-CD22 antibody. Blinatumomab is a bispecific T cell engager antibody comprising the variable regions of the anti-CD19 and the anti-CD3 antibodies. The remission rate of InO is about 75%; however, the frequency of sinusoidal obstruction syndrome is increased when allogeneic hematopoietic cell transplantation is performed after InO treatment. Blinatumomab has a remission rate of 45-70%. The management of cytokine release syndrome during blinatumomab treatment is required in certain cases. Although both the treatments have higher remission and negativity of minimal residual disease rates compared to those in conventional chemotherapy, it is difficult to maintain remission in the long term. Allogeneic hematopoietic stem cell transplantation should be performed as commonly as possible.