A peculiar subtype of glioblastoma multiforme is gliosarcoma. According to histological analysis, it possesses a biphasic shape that clearly distinguishes between glial and sarcomatous tissue. A gliosarcoma is often seen in the supratentorial region. Here, we describe a rare instance of giant left intraventricular gliosarcoma that manifested in a 1-year-old male. Advanced brain scan using magnetic resonance imaging identified a supratentorial tumor with radiological characteristics comparable to choroid plexus carcinoma. Histopathology determined that the tumor was a gliosarcoma. Despite its rarity, gliosarcoma should be taken into consideration when determining the differential diagnosis of intraventricular tumors in children who exhibit radiological signs of choroid plexus carcinoma.