The object of the invention is to provide a new treatment method and treatment device that together with being able to improve a drop in cardiac contractility when treating cardiovascular disease such as acute myocardial infarction and suppress the occurrence of arrhythmia, is able to reduce the infarct size. Provided is an electrical stimulation device for treating cardiovascular disease having at least one electrode that is placed on a nerve site in the body of an animal, and an electrical stimulation application unit that applies electrical stimulation by the electrode to the vagus nerve in the neck region of the animal; and a method for treating cardiovascular disease in an animal having a step of placing an electrode in contact with the vagus nerve in the neck region of an animal, and a step of applying electrical stimulation to the animal.