Three-dimensional CT angiography revealed a patent antethoracic jejunal artery, indicating ischemic jejunitis due to non-occlusive mesenteric ischemia (NOMI) with contraction of the atrait artery of the jejunum, which might be caused by pneumonia. Because there was no evidence of necrosis of the antethoracic jejunum, the patient was conservatively treated for pneumonia and hypovolemia. On the 13th POD, NOMI resolved. Although NOMI of the reconstructed organ can occasionally develop after esophagectomy, conservative therapy may be effective in selected patients in whom NOMI is diagnosed early.