A 49-year-old man lost consciousness after being accidentally exposed to what was probably hydrogen sulfide gas while performing maintenance on a machine producing feather meal. He was immediately taken to the hospital. Upon admission, his consciousness level was 14 (E4V4M6) on the Glasgow Coma Scale (GCS), but it subsequently decreased, and the patient was intubated when his respirations became depressed as well. About 5 hours after the initial incident, he was transferred to our department. His consciousness level was GCS 9 (E2V2M5), his blood pressure was 95/78 mmHg, and his heart rate was 90 beats per min. There was no metabolic acidosis. Mechanical ventilation was begun and 10% sodium nitrite was intermittently administered intravenously, with the goal of lowering arterial blood methemoglobin saturation to 20%. Two days following admission, the patient regained full consciousness and sodium nitrite administration was stopped. The following day mechanical ventilation was also discontinued. This patient exhibited severe recurring neurologic symptoms without metabolic acidosis; thus, the manifestations of toxicity in this case might have been due to the direct neurologic toxicity of hydrogen sulfide, hypoxia, or delayed post-ischemic cerebral hypoperfusion syndrome. The patient made a full recovery without any sequelae; therefore we would like to hypothesize that repetitive intravenous administration of sodium nitrite is effective in cases of hydrogen sulfide exposure.