A 24-year-old woman presented with an abnormal sound in her neck. She had no history of previous surgery, endotracheal intubation or neck trauma. She had been aware of this abnormal sound since she was 12 years old, but paid no attention to it. She had been recommended to visit a hospital for a neck examination. Stridor was heared in the neck ["coming from the throat"?]. Peak flow was markedly suppressed in pulmonary function tests, and the flow volume loop indicated upper airway stenosis. Bronchoscopy revealed subglottic tracheal stenosis, and magnetic resonance imaging showed that the cricoid cartilage was normal. Nd-YAG laser treatment was performed in Mitsui Memorial Hospital and her symptoms were improved. Biopsy of the stenotic area of the trachea showed dense fibrous tissue proliferation in the submucosa. Neither granuloma nor vasculitis was found in the biopsy specimen. No systemic disease capable of inducing tracheal stenosis was found on systemic examination. From these clinical and pathological findings, we diagnosed idiopathic subglottic stenosis.