A case of medullomyoblastoma is described. Partial removal of a cerebellar tumor was performed at the age of 21 months old, and histopathological diagnosis was medulloblastoma. Death occurred at 15 years of age, due to pneumonia and relapse of the tumor. Autopsy revealed well-differentiated muscular and ependymal components disseminated in the medulloblastic area. Immunohistochemically, desmin was positively detected in not only autopsy materials but also undifferentiated cells of the surgical specimens, suggesting prospective myoblastic differentiation.