A search system comprising an information processing device, a search device, and a corresponding keyword management device, the information processing device including a corresponding keyword storage unit that stores corresponding keyword data generated by the corresponding keyword management device as data associating a search keyword with a corresponding keyword group including one or more corresponding keywords; a search keyword input unit that inputs a search keyword; a corresponding keyword group acquisition unit that obtains from the corresponding keyword data stored in the corresponding keyword storage unit a corresponding keyword group associated with the search keyword input by the search keyword input unit; an encrypted keyword group generation unit that encrypts corresponding keywords included in the corresponding keyword group obtained by the corresponding keyword group acquisition unit, thereby generating an encrypted keyword group; a search request data transmission unit that transmits to the search device search request data including the encrypted keyword group generated by the encrypted keyword group generation unit; a search response data receiving unit that receives search response data transmitted from the search device; and a search result output unit that decrypts encrypted data included in the search response data received by the search response data receiving unit, and outputs as a search result search data obtained by decryption, the search device including an encrypted data storage unit that stores encrypted data generated by encrypting each search data and an encrypted keyword generated by encrypting a corresponding keyword, the encrypted data and the encrypted keyword being associated with each other; a search request data receiving unit that receives the search request data transmitted by the information processing device; an encrypted data search unit that obtains encrypted data associated with a search key from the encrypted data storage unit using as the search key an encrypted keyword included in the encrypted keyword group in the search request data, based on the search request data received by the search request data receiving unit; and a search response data transmission unit that transmits the search response data including the encrypted data obtained by the encrypted data search unit, the corresponding keyword management device including an appearance frequency storage unit that stores appearance frequency data defining a search keyword and an appearance frequency of the search keyword, the appearance frequency indicating a rate of search data associated with the search keyword; a corresponding keyword number calculation unit that calculates as a corresponding keyword number a number of corresponding keywords to be associated with the search keyword, according to the appearance frequency of the search keyword defined in the appearance frequency data stored in the appearance frequency storage unit; a corresponding keyword group generation unit that generates as a corresponding keyword group a same number of corresponding keywords as the corresponding keyword number calculated by the corresponding keyword number calculation unit; and a corresponding keyword data generation unit that generates the corresponding keyword data by associating the search keyword defined in the appearance frequency data with the corresponding keyword group generated by the corresponding keyword group generation unit.