1. A camera system, comprising: a plurality of cameras; an information-processing device, which is connected through a communication network with the plurality of cameras, and which acquires a shot image from the plurality of cameras, wherein the plurality of cameras each includes an image-pickup part operable to take an image of a subject, and an image-pickup synchronizing part operable to mutually synchronize an image-pickup timing of the camera with an image-pickup timing of another one of the cameras, and wherein the information-processing device includes a synchronous shot image-acquiring part operable to acquire a shot image taken by each of the cameras at a common timing from the cameras, an image-evaluating part operable to evaluate a condition of the subject in each shot image concerning each of the shot images taken at a common timing acquired by the synchronous shot image-acquiring part based on predetermined evaluation criteria and to assign an evaluation value to each shot image, a prioritizing part operable to assign a priority to each of the shot images according to the evaluation value assigned to each shot image by the image-evaluating part, and a display control part operable to make a display device display the shot images according to the priorities assigned to the shot images by the prioritizing part.