An image output system configured of information terminals, each of which includes an identification information storage unit which stores identification information for identifying each of the information terminals and a transmission unit which transmits the identification information, and an image output apparatus which includes: an identification information receiving unit which receives the identification information transmitted by each of the information terminals; an output unit which obtains image information which is information for outputting images, and outputs images based on the obtained image information; a judgment unit which judges whether or not plural pieces of identification received by the identification information receiving unit satisfy a predetermined condition; and an output control unit which controls the output unit based on the judgment made by the judgment unit.