A network system includes an image projection apparatus that projects image data; a first terminal; and a second terminal where the first terminal includes an original image data storing unit that stores original image data and a corresponding information generating unit that generates corresponding information in which image identification data of the image data for projection, generated from the original image data, capable of identifying the original image data and terminal identification data for identifying the first terminal correspond with each other, and the image projection apparatus includes a corresponding information sending unit that sends, upon receiving the request for delivering the corresponding information of the image data being projected from the second terminal, the corresponding information stored in the storing unit, to the second terminal.