To provide an identification information management method for generating unique identification information which is not superposed with already-generated identification information even if confidential information is changed to new one when the confidential information leaks out.

This identification information management method for generating identification information based on management information and confidential information includes: a first input step for dividing management information inputted from the outside into a plurality of partial management information and outputting them; a second input step for dividing the confidential information inputted from the outside into a plurality of partial confidential information and outputting them; a partial identification information generation step for inputting each of the plurality of partial management information and the plurality of partial confidential information to a partial information generation part corresponding to each of the partial management information and the partial management information, and for generating partial identification information based on the partial management information and the partial confidential information by each partial information generation part; and an output step for generating identification information by connecting the plurality of partial identification information generated by the partial identification information generation step.