To provide an image information authentication system capable renting a vehicle having an ecology authentication system to a third party.

The image information authentication system 10 is an ecology authentication system in which, in an on-vehicle computer 14 mounted on a vehicle 12 such as an automobile, when a person detection sensor 16 detects that a person approaches a detection area (close to a driver's seat side door) of the vehicle 12, a driver is image-picked up by an on-vehicle camera 18, and various kinds of instruments of the vehicle 12 can be operated under the condition that picked-up image information is matched with image information registered in advance. When an owner of the vehicle 12 rents the vehicle 12 to a third party, a face of the third party is image-picked up by a cellular phone 40 with a camera, and the image information of the third party is transmitted to a center 36. Registration can be performed in the vehicle 12 so that the ecological authentication of the third party is performed.