During the early stage of postherpetic neuralgia, an epidural block on the affected segment is helpful in controlling pain and preventing progression to a chronic state. The main neurologic complication following an epidural block is cord compression symptom due to an epidural hematoma. When neurologic complications arise from an epidural block for the treatment of postherpetic neuralgia, it is important to determine whether the complications are due to the procedure or due to the herpes zoster itself. We report a case of a patient who was diagnosed with herpes zoster myelitis during treatment for postherpetic neuralgia. The patient complained of motor weakness in the lower extremities after receiving a thoracic epidural block six times. Although initially, we believed that the complications were due to the epidural block, it was ultimately determined to be from the herpes zoster myelitis.