Obesity is widely recognized as a risk factor for coronary artery disease, but opinion is divided regarding whether it is an independent risk factor for cerebrovascular disease; even now there is no common view. In this study, the review sought to focus on a prospective study, but since obesity and non-obesity basically cannot be randomly assigned, randomized controlled trials (RCT) are nonexistent. Accordingly, a cohort study (a method of clinical study in which the obesity group is actively followed up for comparison with the non-obesity group in regard to cerebrovascular disease) was mainly conducted. For reference, retrospective case-control studies are also shown. As a result, most epidemiological surveys on the relation between simple obesity and cerebrovascular disease denied any relation. That is, obesity alone, determined only on the basis of height and weight as shown by BMI (body mass index), etc., cannot be an independent risk factor for cerebrovascular disease; obesity can become a risk factor only when accompanied by hypertension, hyperlipidemia, impaired glucose tolerance, etc. Recently, however, most papers conclude that abdominal obesity is a risk factor for cerebral infarction, provided that there are no data confirming that obesity is a risk factor for hemorrhagic cerebrovascular disease (cerebral hemorrhage and subarachnoid hemorrhage).