Extracranial carotid artery aneurysms are relatively rare. We present a case involving a giant aneurysm arising from the extracranial carotid artery. The patient was a 79-year-old woman. She had a pulsating mass in the right side of her neck. However, she was neurologically intact. Contrast-enhanced CT scans of the neck showed an enhanced mass lesion with a thrombus in the right side of her neck. Angiography revealed a saccular aneurysm 3.4 cm in size near the bifurcation site of the right common carotid artery into the external carotid artery. She underwent an urgent resection of the aneurysm and a carotid artery reconstruction. Postoperatively, she recovered well and the total resection of the lesion was angiographically confirmed. Histopathological examination revealed that the wall of the aneurysm had undergone fibrosis and contained a few elastic fibers and microhemorrhages. The wall of the aneurysm was also infiltrated by inflammatory cells. The surgical strategy for and appropriate preoperative evaluation of this rare disease was discussed.