A 58-year-old man presented with a rare case of glioblastoma masquerading as intracerebral hemorrhage (ICH). He had been medicated for hypertension and diabetes for 10 years before collapsing at home. Brain computed tomography (CT) showed ICH in the right putamen, but CT with contrast medium showed no underlying lesion. He was treated initially with intravenous administration of anti-hypertensive agent under a diagnosis of hypertensive putaminal hemorrhage. ICH aspiration surgery was performed, and serial CT showed ICH resorption. However, he was again admitted for unstable gait and mildly altered mental status 3 months after discharge. Magnetic resonance (MR) imaging with gadolinium showed an enhanced ring-shaped mass around the hematoma cavity. Open biopsy was performed. The histological diagnosis was glioblastoma multiforme, and he was treated with radiation therapy and oral chemotherapy with temozolomide. MR imaging showed marked shrinkage of the tumor, but he died of pneumonia 3 months after the second surgery. In this case, the cause of the hemorrhage was not identified after the seemingly successful hematoma evacuation surgery, and no definitive diagnosis was made until tumor regrowth. Brain tumor should be suspected as a cause of ICH even if the patient has a history of hypertension and the location is typical for hypertensive ICH. Clinical/radiological follow up is essential for detecting subtle neurological deterioration to avoid diagnostic delay.