Impairment of executive functions (EFs) was investigated in patients with cerebral hypoperfusion after cerebral angiostenosis/occlusion. Several EFs were measured in patients with cerebral angiostenosis/occlusion and healthy subjects. The vascular conditions, regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), mean transit time (MTT), time to peak (TTP), and delay time were assessed. The scores of the vascular stenosis/occlusion group were significantly lower than those of the control group. rCBV and rCBF were negatively correlated with the error response times in the Stroop test, and the persistent error responses in the Wisconsin Card Sorting Test (WCST) were positively correlated with the Montreal Cognitive Assessment (MoCA) scores. TTP was positively correlated with the reaction and error reaction times, and the persistent error response in WCST was negatively correlated with the times of sorting in WCST and MoCA scores. MTT was positively correlated with the persistent error response in WCST. In the Stroop test, delay time was positively correlated with response time, and negatively correlated with error response times, and the persistent error response in WCST and MoCA scores. Patients with cerebral hypoperfusion after cerebral angiostenosis/occlusion had executive dysfunctions in working memory, sustained attention, response inhibition, cognitive flexibility, thought organization, planning, and implementation. Moreover, their executive dysfunctions were related with the decline in rCBF and rCBV. The prolonged TTP, MTT, and delay time suggested a slow blood flow and the poor compensation of collateral circulation, resulting in impairment of the EFs.