A spontaneous dissecting aneurysm of visceral arteries without trauma or an iatrogenic cause is rare. We would like to report a case of a dissecting aneurysm of the common and proper hepatic artery with dissection of the celiac axis and the superior mesenteric artery (SMA). A 55-year-old man presented abdominal pain. In the abdominal computed tomography (CT), an intraabdominal hematoma and a dissecting aneurysm of the common and proper hepatic artery with dissection of the celiac axis as well as the SMA had been found. The size of the dissecting aneurysm was growing in a follow-up CT. We performed a bypass between the right hepatic artery and a celiac artery with a saphenous vein after exclusion of the aneurysm. A bypass graft was occluded in the early postoperative period but the patient recovered without major sequelae.