We reported a 64-year-old man who had malignant rheumatoid arthritis (MRA) and developed subacute myelopathy and peripheral neuropathy. He had suffered from seropositive rheumatoid arthritis for 4 years, and developed weakness of four limbs, dysuria and constipation two months before the admission. Neurological examination revealed the diffuse muscle wasting and weakness in four limbs. Deep tendon reflexes were hyperactive in four limbs, but not in jaw jerk. Babinski sign was positive bilaterally. Deep sensation was decreased in four limbs and superficial sensation was decreased below the neck. Dysuria and constipation were noted, but anal and bulbocavernosus reflexes were present. On laboratory examination, RF and RAHA increased markedly. Serum complements decreased and immune complexes were positive. Nerve conduction study demonstrated multiple entrapment neuropathy in addition to mononeuritis multiplex. Histological examination of the biopsied sural nerve disclosed the obliterating endarteritis in the epineurium, and marked decrease in number of myelinated fibers. No compressive lesions were seen in the spinal canal by spine X-ray and MRI. Assuming that inflammatory process induced cervical myelopathy, corticosteroid therapy (predonisolone 60 mg/day) was administered and alleviated neurological symptoms, in accordance with the improvement of serological abnormalities. Therefore, an inflammatory process associated with MRA was supposed to damage the spinal cord as well as peripheral nerves in the present case.