A 9-year-old girl struck the left side of her head on a doorknob, after which she gradually developed swelling. She was treated conservatively at another hospital before being referred and admitted to our hospital 9 days after injury, with complaints of exophthalmos and diplopia. Computed tomography (CT) scanning and magnetic resonance imaging (MRI) revealed a subgaleal hematoma (SGH). We therefore attempted to treat the patient by aspiration of the hematoma via needle puncture through the skin, for which we wrapped an elastic band around the head while infusing a hemostatic agent. No vascular anomalies and no abnormal shunts were identified by angiography under general anesthesia 13 days after injury. The patient was treated surgically due to increased head swelling and deteriorated exophthalmos. The liquefied, dark-red SGH was aspirated via a few cm of skin and a galeal incision on the left side of her head. A multiperforated drainage catheter was introduced into the hematoma cavity and the drainage catheter was connected to the vacuum-drain pump. After the surgery, the left exophthalmos disappeared. Twenty-three days after injury, she was discharged from our hospital without any neurological deficits.