Parking assist systems, methods and programs identify a position of a vehicle and obtain image data of an area around the vehicle from a camera on the vehicle. The systems, methods, and programs associate the obtained image data with a position of the vehicle where the image data was obtained and store the obtained image data and the associated position of the vehicle as past image data in a memory. The systems, methods, and programs determine whether the vehicle has at least entered a target parking area and display, based on the determination, an image on a display unit, the displayed image based on the past image data and image data taken at a current position of the vehicle.