Although cytomegalovirus (CMV) retinitis is usually diagnosed in allogeneic hematopoietic cell transplantation recipients among patients with hematologic and oncologic disease, it can also occur in acute leukemia patients who have not received hematopoietic cell transplantation. However, CMV retinitis diagnosed after completion of chemotherapy for acute leukemia has not previously been reported. A 17-year-old boy was diagnosed with CMV retinitis 3 months after completion of chemotherapy for acute lymphoblastic leukemia, and his retinitis was assumed to be caused by a delayed immune reconstitution after chemotherapy. The patient was treated with intravenous and intravitreous ganciclovir therapy, and subsequently underwent surgery for retinal detachment.