A 9-year-old female suddenly developed headache and nausea. Computed tomography (CT) revealed pineal mass lesion and obstructive hydrocephalus. One week after the onset, hydrocephalus spontaneously resolved. Magnetic resonance imaging (MRI) revealed that the mass was a subacute hematoma and that hydrocephalus had improved. Sequential MRI 4 months later revealed an enhanced lesion in the pineal region. Total removal of the tumor by the occipital transtentorial approach established the histopathological diagnosis of pineoblastoma.