A 5-year-old child suffering from fever, vomiting and convulsions was transported to an emergency medical center. He was administered anticonvulsant and performed tracheal intubation. A diagnosis of acute encephalopathy caused by 2009 influenza A (H1N1) was made, and the child was admitted to our hospital. He was admitted to the ICU and initiated on mechanical ventilation under sedation and treatment of brain edema. After that he never had convulsions. On hospital day 7, he woke up under administration of only dexmedetomidine, and extubation was performed. However, thereafter, the child developed stridor suggestive of upper airway stenosis, labored breathing with intercostal retraction, and tachypnea. Therefore, noninvasive positive pressure ventilation (NPPV) was initiated using a helmet (CASTER “R” for children). There was little air leak, and the respiratory condition showed prompt improvement. There were no problems with the use of helmet NPPV, and we could communicate successfully with the child and hear his voice. The following day, he could be weaned off from the NPPV, and re-intubation could be avoided. These findings suggest that the helmet may be a useful device for NPPV in children, because it doesn't appear to give rise to a feeling of suffocation, and has high acceptability even among children.