Ovarian clear cell adenocarcinoma (OCCA) is known to have a worse prognosis than ovarian serous adenocarcinoma due to its poor response to conventional platinum-based chemotherapy. Idiopathic thrombocytopenic purpura (ITP), which usually reveals severe thrombocytopenia, is a common autoimmune disorder. However, to date very few cases of ovarian cancer associated with ITP have been reported in the literature. We report a case of a 57-year-old woman who developed OCCA 14 years after the diagnosis of ITP. The patient presented with abdominal distention and mild tenderness. We performed the operation with high-dose immunoglobulin therapy preoperatively, and diagnosed OCCA. Postoperatively, six cycles of cytotoxic chemotherapy with irinotecan hydrochloride plus cisplatin were performed every 4-5 weeks without thrombocytopenia. We conclude that combination chemotherapy with irinotecan hydrochloride plus cisplatin is useful for a case of OCCA associated with ITP.