A central person determining system includes an information terminal having a plurality of image data; and a server; wherein the information terminal performs face detection processing and generates a face detection result for each of a plurality of images based on the plurality of image data, generates a plurality of face image data by cropping, on the basis of the face detection result, a face image from the plurality of images based on the plurality of image data, and transmits the plurality of face image data to the server; and wherein the server performs central person determining processing on the basis of the plurality of face image data acquired from the information terminal, generates the central person determining result, and transmits the central person determining result to the information terminal.