1. An image recognition device which outputs, as a recognition result, information indicating what an input image is, said image recognition device comprising: an image input unit configured to obtain the input image which is a target image to be recognized; a similar image search unit configured to search out at least one similar image which is similar to the target image obtained by said image input unit from among images generated independently of said image recognition device, stored in a server device accessible via the Internet, and unintentionally obtained; a keyword extraction unit configured to extract a plurality of keywords which are candidates for a recognition result of the target image, from attached information which is attached to the at least one similar image searched out by said similar image search unit; a keyword analysis unit configured to determine at least one likely keyword which is likely to be the recognition result of the target image from among the plurality of keywords extracted by said keyword extraction unit by analyzing the plurality of keywords; and a presentation unit configured to output the at least one likely keyword determined by said keyword analysis unit, as the recognition result of the target image.