Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia caused by immune-mediated platelet destruction and impairment of platelet production. Recent studies have uncovered details involving the target regions of platelet-associated anti-GPIIb/IIIa antibodies, pathological differences depending on the specificity of target antigens, and cellular abnormalities, especially impairment of regulatory T cells contributing to the pathogenesis of ITP. Treatment of ITP has been changed dramatically by the application of thrombopoietin receptor agonists, TPO-RAs, in patients unresponsive to traditional steroids and splenectomy. Rituximab has also been used in Western countries for ITP patients and its long-term efficacy has become increasingly clear. Clinical problems awaiting solution in ITP management include improving the efficacy of treatments for newly-diagnosed ITP, confirmation of the long-term efficacy and safety of TPO-RAs, and determination of the positioning of rituximab in the treatment sequence of ITP.