We have been experienced a rare case of large supratentorial neuroepithelial tumor with a subdural cyst originated from the left fronto-parietal lobe in a 14-month-old boy. The tumor was characterized by its voluminous size, a leptomeningeal growth pattern with intense desmoplasia and divergent astrocytic and ganglionic differentiation. Schwann cell differentiation and melanocytes were also minutely demonstrated. These histological findings are characteristic of desmoplastic infantile gangliogliomas, reported by VandenBerg et al in 1987. And this tumor tissue architecture strongly suggests the hamartomatous nature, rather than the ordinary neoplastic lesion.