We report a 39-year-old woman with slowly progressive spastic gait and paresthesia in the lower extremities. Cervical spinal MRI revealed high intensity in the dorsal column from vertebrae C2 to C7. Laboratory findings showed normal vitamin B12 and low serum copper level. By lifestyle history taking, we noticed her extreme unbalanced diet of having 15-20 oysters everyday over 5 years. Then we considered that zinc excess caused copper deficiency myelopathy. We needed to pay attention to copper and zinc level if the patient has a symptom resembling subacute combined degeneration of spinal cord with normal serum vitamin B12.