PROBLEM TO BE SOLVED: To foresee an object person's possibility of dementia without his/her taking a dementia test in a medical institution.SOLUTION: Provided is a system for foreseeing dementia which comprises: an input information acquisition part S43 for acquiring operation input data entered by an object person on the promise of making it known that he/she is fine everyday by pressing a button; a dementia possibility determination part S46 for determining whether the operation input data meets dementia possibility determination criteria; and a dementia possibility notification part S47 for making it known that the object person may be demented if the operation input data meets the dementia possibility determination criteria.