Fibromuscular dysplasia (FMD) can develop in many different arteries, but iliac artery aneurysms are rare. A 69-year-old Japanese woman was admitted to our hospital for treatment of a right common iliac artery aneurysm. Aortography revealed aneurysms in both the right common iliac artery and the left internal iliac artery. Notably, the right common iliac artery aneurysm had a "string-of-beads" appearance. At surgery, the aneurysms were resected, and replaced with Y-shaped vascular prostheses. The histopathological diagnosis was fibromuscular dysplasia (FMD). We report this case of common iliac artery aneurysm caused by FMD due to its rarity.