A 39 year-old man was admitted to this hospital because of severe headache and vomiting. He had been suffering from lumbago about one month previously, and diplopia ten days previously. The neurological examination revealed disturbance of right eye abduction, no nuchal rigidity. The cerebrospinal fluid (CSF) at the time of admission included erythrocytes (1,490/μl), white blood cell (62/μl) and increased level of protein (531 mg/dl), but no malignant cells were detected. He was treated as meningitis. Cranial magnetic resonance imaging (MRI) demonstrated heterogeneous intensity lesion in the left maxillary sinus and gadolinium enhancement of diffuse meninges and cranial nerves. Spine MRI showed gadolinium enhancement of lumbar spinal meninges and the cauda equina. Biopsy of the lesion in the left maxillary sinus was performed. The pathological findings demonstrated malignant melanoma. Because malignant cells were also observed in CSF, we diagnosed this case as leptomeningeal melanomatosis. Leptomeningeal carcinomatosis should be suspected when headache accompanied with pleomorphic clinical manifestations.