We report a patient who had rhinogenic intracranial complication with postoperative frontal sinus pyocele and inverted papilloma in the nasal cavity. A 72-year-old woman had undergone surgery for frontal sinusitis via external incision at another hospital 13 years previously. Left-sided hemiparesis appeared in the patient and gradually worsened. Five days later, she exhibited disorientation, abnormal behavior, poor articulation, and difficulty in standing. Therefore, she was taken to the neurosurgery department by ambulance. An extensive frontal sinus pyocele was suspected, and a cerebral abscess and edema of the frontal lobe were observed on magnetic resonance imaging. After antibiotics, steroid and glycerol were administered for a few weeks; disorientation and left hemiparesis improved. Next, craniotomy for complete removal of the brain abscess by neurosurgeons and endoscopic endonasal surgery by otolaryngologists were carried out at the same surgery. From the analysis of the pathological mucosa sample taken from the right ethomoidal sinus during surgery, an inverted papilloma was diagnosed. The patient completely recovered and is currently receiving follow-up examination. Regarding rhinogenic intracranial complications, ascertaining clinical condition in order to determine the need for either immediate radical surgery, or for curative surgery after waiting for improvement of the overall body condition by conservative management, is still needed.