Carotid artery stenting (CAS) has been developed as an alternative therapeutic strategy of carotid endarterectomy (CEA) both for symptomatic and asymptomatic extra-cranial carotid artery stenosis. Some randomized clinical trial has been successfully proven the non-inferiority of CAS compared to CEA in terms of efficacy and safety regarding freedom from major adverse event (MAE). One of the remaining problems in CAS is a non-significant but relatively higher incidence of ipsi-lateral minor stroke related to the procedure, both during and soon after the procedure. We routinely examine intravascular ultrasound (IVUS) imaging during the CAS procedure, and found some informative findings. We hereby report the representative IVUS finding, which might suggest the possible cause for delayed stroke after CAS.