Based on captured images obtained when an image capture device takes images in an image capture range, a change in the moving speed of one passerby or each of a plurality of passerby contained in the captured images is calculated. When there is a passerby whose moving speed is decreased in the image capture range, the passerby is paying attention to the content, and therefore content to be outputted by a content output device is switched from ordinary content to specific content. On the other hand, when only passerby who are moving at constant speed are present in the image capture range, the passerby are not paying attention to the content, and hence the content output device continues to output the ordinary content.