An information processing system comprising: an image search system configured to search, for an image to be found, databases (11 lb; 111b1; 111b2) in accordance with a search request and based on similarity of feature information extracted from the image to be found to feature information extracted from a search key image which is a received captured image, the databases (111b; 111b1; 111b2) having the image to be found, the feature information extracted from the image to be found and linkage information registered therein in association with each other, and transmit the linkage information associated with the image to be found to a transmitter of the search request when the image to be found is found, characterized in that the system further comprises a customer-side system operated by a customer of the image search system, and in that the image search system comprises: a module distributer configured to distribute a search module (311a1) and a piece of module identification information (312a1) to the customer-side system while associating the search module (311a1) and the piece of module identification information (312a1) with each other, the search module (311a1) being used for causing a terminal device to transmit the search request to a searcher, the piece of module identification information being used for identifying the search module (311a1); and the searcher configured to, as a result of causing the search module (311a1) to run on the terminal device, execute the searching of the databases (111b; 111b1; 11 lb2) in accordance with the module identification information (312a1) included in the search request transmitted from the terminal device, wherein the piece of module identification information is one of a plurality of pieces of module identification information, the search module (311a1) is one of a plurality of search modules (311a1; 311a2), and the module distributer distributes, to the customer-side system, the search modules associated with the different pieces of module identification information. an image search system configured to search, for an image to be found, databases (11 lb; 111b1; 111b2) in accordance with a search request and based on similarity of feature information extracted from the image to be found to feature information extracted from a search key image which is a received captured image, the databases (111b; 111b1; 111b2) having the image to be found, the feature information extracted from the image to be found and linkage information registered therein in association with each other, and transmit the linkage information associated with the image to be found to a transmitter of the search request when the image to be found is found, characterized in that the system further comprises a customer-side system operated by a customer of the image search system, and in that the image search system comprises: a module distributer configured to distribute a search module (311a1) and a piece of module identification information (312a1) to the customer-side system while associating the search module (311a1) and the piece of module identification information (312a1) with each other, the search module (311a1) being used for causing a terminal device to transmit the search request to a searcher, the piece of module identification information being used for identifying the search module (311a1); and the searcher configured to, as a result of causing the search module (311a1) to run on the terminal device, execute the searching of the databases (111b; 111b1; 11 lb2) in accordance with the module identification information (312a1) included in the search request transmitted from the terminal device, wherein the piece of module identification information is one of a plurality of pieces of module identification information, the search module (311a1) is one of a plurality of search modules (311a1; 311a2), and the module distributer distributes, to the customer-side system, the search modules associated with the different pieces of module identification information. a module distributer configured to distribute a search module (311a1) and a piece of module identification information (312a1) to the customer-side system while associating the search module (311a1) and the piece of module identification information (312a1) with each other, the search module (311a1) being used for causing a terminal device to transmit the search request to a searcher, the piece of module identification information being used for identifying the search module (311a1); and the searcher configured to, as a result of causing the search module (311a1) to run on the terminal device, execute the searching of the databases (111b; 111b1; 11 lb2) in accordance with the module identification information (312a1) included in the search request transmitted from the terminal device, wherein the piece of module identification information is one of a plurality of pieces of module identification information, the search module (311a1) is one of a plurality of search modules (311a1; 311a2), and the module distributer distributes, to the customer-side system, the search modules associated with the different pieces of module identification information.