Spontaneous rupture of the common carotid artery is extremely rare vascular disorder. Pseudoaneurysm is usually formed by arterial rupture and it is presented clinically as expanding mass lesion. The mass may be pulsatile and a bruit may be present. A 37-year-old man suffered from the spontaneous rupture of the left common carotid artery and resultant pseudoaneurysm formation was found radiologically. Elective surgical exploration revealed a 0.5cm rent in the common carotid artery, 2cm proximal from the bifurcation. Large amount of thrombi were found in the aneurysmal sac. The lesion was successfully treated with polypropylene sutures during temporary clamping of the carotid artery. He recovered without any complication such as neurological sequelaes. Postoperative angiography revealed a good patency of the repaired common carotid artery.