Meningioma is a common primary tumor of central nervous system. However, extracranial extension of the intracranial meningioma is unusual, and mostly accompanied the osteolytic change of the skull. We herein describe an atypical meningioma having extracranial extension with hyperostotic change of the skull. The patient was a 72-year-old woman who presented a large mass in the right frontal scalp and left hemiparesis. Brain magnetic resonance imaging and computed tomography scans revealed an intracranial mass, diffuse meningeal thickening, hyperostotic change of the skull with focal extension into the right frontal scalp. She underwent total removal of extracranial tumor, bifrontal craniectomy, and partial removal of intracranial tumor followed by cranioplasty. Tumor pathology was confirmed as atypical meningioma, and she received adjuvant radiotherapy. In this report, we present and discuss a meningioma en plaque of atypical histopathology having an extracranial extension with diffuse intracranial growth and hyperostotic change of the skull.