An 80-year-old man felt a loss of strength and sharp pain in both lower limbs while playing gate-ball, consulted a nearby doctor, and was followed up. Because the sharp pains in both lower limbs became aggravated the next day, he was given a previously prescribed medication. Both femoral pulses were absent and acute arterial obstruction of the lower limbs was suspected. A contrast-enhanced CT scan showed a thrombosed infrarenal abdominal aortic aneurysm with a maximum transverse diameter of 37 mm, and both external iliac arteries were contrast imaged by collateral circulation pathways. We diagnosed acute thrombosis of an abdominal aortic aneurysm, and was urgently transported to our hospital. We classified his lower limbs as Balas grade III and TASC classification grade IIb and Rutherford classification grade IIb. He exhibited no abdominal symptoms and since we confirmed the blood flow of his lower limbs, we decided to perform revascularization. An extra-anatomical bypass (axillo-bifemoral bypass) was conducted because he had dementia, and was old. After the operation, myonephropathic metabolic syndrome (MNMS) did not develop, and the patient was discharged on foot on the 16th postoperative day. Acute thrombosis of an abdominal aortic aneurysm is a rare disease. Because the ischemic area widens, often causing serious MNMS after the revascularization, it has a poor prognosis. Here, we report a case in which one such patient was rescued.