Intestinal malrotation occurs because of an arrest of normal rotation of the embryonic gut. It is often diagnosed in first month of life because of acute complications and requires surgical management. If it is not detected at a young age, it is diagnosed incidentally in advanced age. It is very rarely reported at advanced age with symptoms. In Korea in the last 30 years only about 10 such cases have been reported. In 2010, intestinal malrotation was reported at advanced age in only one case who had acute duodenal obstruction due to non-rotation of the pre-arterial segment of mid-gut. Therefore, we report a case of a 45-year-old man with non-rotation of pre-arterial segment with duodenal obstruction who had complained chronic and mild epigastric discomfort from a year ago.