The present disclosure relates to a device and method for inducing improvement of cerebral circulation by using light energy, i.e., photo-innervated neuro-stimulation (PINS), and stimulating nerve endings distributed in the epidermis or dermis located below a skin surface in an area corresponding to the carotid artery or an area corresponding to the vertebral artery of the cervix so that blood vessels (vascular muscles) in the brain are relaxed.The present disclosure can be utilized in treating or preventing vascular dementia and Alzheimer's disease, which are caused by the lack of cerebral circulation, and various other brain-related diseases, such as stroke, migraine, depression, and Parkinson's disease, and improving learning ability, memory, and concentration.