Noonan syndrome (NS) is an autosomal dominant disorder in some cases caused by PTPN11 mutations. Since somatic mutations in PTPN11 are seen in several tumor types, NS which causes germline PTPN11 mutations are also increase the risk of hematologic malignancies and brain solid tumors. However, the report of brain tumors in Noonan syndrome remains rather rare. Here, we report the first case of an 11-year-old Thai boy with Noonan syndrome who presented with symptoms related to hydrocephalus secondary to subependymoma in the fourth ventricle, and PTPN11 mutation was identified in this patient.