A non-recurrent laryngeal nerve is a rare nerve anomaly that is associated with a developmentally aberrant subclavian artery. During thyroidectomy,this aberrant nerve may become inadvertently damaged, causing permanent ipsilateral vocal cord paralysis. However, it is possible to predict the presence of a non-recurrent laryngeal nerve by preoperative diagnosis of an aberrant subclavian artery. We report a case of thyroid surgery associated with a right non-recurrent laryngeal nerve that was unnoticed preoperatively in a CT scan of the neck, but was encountered incidentally during the thyroidectomy. The preoperative CT scan showed a retroesophageal aberrant right subclavian artery, but it was unnoticed. The female patient underwent a total thyroidectomy with central compartment node dissection for a thyroid cancer. The recurrent laryngeal nerve on the left side was identified, as was the non-recurrent laryngeal nerve on the right side. Postoperatively, the patient had normal vocal cord function. It is possible to predict preoperatively a right non-recurrent laryngeal nerve by identifying an aberrant right subclavian artery on the CT scan of the neck, which likely enables prevention of vocal cord paralysis.