A 31-year-old woman with pure red cell aplasia presented with motor aphasia and right homonymous hemianopia due to a left temporal and parietal lobe infarction. Magnetic resonance angiography revealed an occlusion of the left anterior and middle cerebral artery, with the development of moyamoya vessels. She was diagnosed with quasi-moyamoya disease and subsequently underwent direct and indirect anastomosis surgery, while continuing steroid and immunosuppressant therapy for pure red cell aplasia. The postoperative course was uneventful, and follow-up cerebral angiography 6 months after the surgery revealed the development of neovascularization through an indirect anastomosis. Neovascularization can be induced while the patient is receiving steroid and immunosuppressant therapy in quasi-moyamoya disease.