Intramedullary spinal cord hemorrhage (hematomyelia) is rare and usually related to trauma. Spinal vascular malformations such as intramedullary cavernomas and intradural arteriovenous malformations are the most common cause of atraumatic hematomyelia. Other considerations include warfarin or heparin anticoagulation, bleeding disorders, spinal cord tumors, and delayed complication of spinal radiation. We report the case of 48-year-old man receiving warfarin and aspirin therapy, who showed upper limb pain and dysesthesia from left axilla to left femur. Paraplegia, sensory disturbance, bladder and rectal disturbance developed gradually over two weeks, accompanied by severe back and neck pain. MRI showed hematomyelia extending from the C1 to T11 segments of the spinal cord. The hemorrhage was located mainly in the left side of the posterior column. Few cases of hematomyelia extending over 18 segments of the spinal cord have been reported. Past literature reports of hematomyelia tend to extend longitudinally above and below the area of initial hemorrhage. We thought that the shape of this hematomyelia extending longitudinally over several segments was formed by a similar pathogenesis to pencil-shaped softening of the spinal cord.