Nuss procedure was recently introduced, because of its excellent effect from the cosmetic point of view and improvement of the pulmonary function, but the complications such as heart injury, bar displacement, hemothorax, pneumothorax and tension pneumothorax sometimes occur. We experienced a 12 year-old female, who showed profound hypotension with a bradycardia and severe reduction in oxygen saturation followed by the tension pneumothorax after the operation by the Nuss method. The patient was treated with the immediate thoracostomy and recovered without any other problem. In anesthetic management of the pectus excavatum repair by the Nuss method, we should always pay attention to the possible occurrence of tension pneumothorax.