Small saccular aneurysm in the right gastroepiploic artery is a sporadic disease accounting for approximately 0.4% of abdominal visceral aneurysms rarely observed during routine examination of other illnesses; however, it has been reported following rupture. The right gastroepiploic artery is a common alternative to the internal thoracic artery in coronary artery bypass grafting. We report a case of small aneurysms in the left anterior descending artery, diagonal branch artery, and right gastroepiploic artery and a pseudoaneurysm in right gastroepiploic artery. Coronary artery bypass grafting was performed using the left internal thoracic artery and right gastroepiploic artery, and a 5-mm aneurysm was observed in the right gastroepiploic artery. The resected 5-mm right gastroepiploic artery aneurysm was saccular. Pathological investigation revealed media loss and adventitial thinning, indicating the possibility of an aneurysm rupture. Thus, preoperative three-dimensional computed tomography is beneficial for patients with coronary arterial aneurysms and preoperative evaluation of right gastroepiploic artery to help achieve good clinical outcomes in patients undergoing coronary artery bypass grafting with another arterial aneurysm.