Ifosfamide, which is widely used as a chemotherapeutic agent in various kinds of malignancies, sometimes causes neurotoxicity known as ifosfamide-induced encephalopathy (IIE). Herein, we report the case of a three-year-old girl who developed IIE during chemotherapy for Ewing's sarcoma and was treated with methylene blue as a prophylactic agent for IIE, after which she continued with ifosfamide and completed treatment without IIE recurrence. This case suggests that methylene blue may be effective in preventing the recurrence of IIE in pediatric patients. Further studies, including clinical trials, are needed to confirm the efficacy and safety of methylene blue in pediatric patients.