Renal artery aneurysm is a rare condition, but its incidence has increased through discovery because of improved imaging techniques. However, a therapeutic approach for renal artery aneurysm has not been established. We report the case of a 58-year-old female who had developed hypertension at 52 years of age and was under oral medication for this condition. In a medical check-up, a right renal artery aneurysm of 10 mm in diameter was detected by computed tomography (CT). Renal function was normal and there were no abnormalities in urinalysis; therefore, the patient was observed as an outpatient. Abdominal CT performed 9 months later revealed a saccular renal artery aneurysm of 15 mm in diameter with partial wall calcification and mild mural thrombus. Selective right renal arteriography detected a tumor with calcification, but no renal arterial stenosis or renal arteriovenous fistula. Since the aneurysm had enlarged, catheter treatment was selected to reduce the risk of rupture. A 6-Fr guide catheter was inserted into the right renal artery and the tip of a microcoil catheter was advanced into the aneurysm, which was then embolized with 12 microcoils. The absence of the aneurysm was confirmed using right renal arteriography. No complications occurred during or after embolization, and selective right renal arteriography performed 3 months later showed no change in the coil position or blood flow in the aneurysm, suggesting a good postoperative course. Our results suggest that this approach may generally be applicable for renal artery aneurysms, depending on the shape, size, and location of the aneurysm.