A search system has a management device that stores compound data and a searcher device. The management device defines a similarity between query sequence data q representing a substructure or property of a substance that is input as a search condition at the searcher device and sequence data pi (i=1, 2, . . . , m) for substances stored in the database by means of a score T that takes a non-negative value when a Tversky index Si is greater than or equal to a threshold value θn/θd (where θn and θd are natural numbers that satisfy θn≦θd), calculates an encrypted value of the score T while the query sequence q is maintained in an encrypted state, and returns the encrypted value to the searcher device to thereby disclose information regarding whether or not similar compounds are present in the database while in a confidential state.