PURPOSE: To quickly take out and return a retrieval result from a population and to easily affect the state change of the population on the retrieval result by providing and operating a retrieval result list and history information in a retrieval result holding method to hold the retrieval result from the population.

CONSTITUTION: This method is comprised of the population 1 on which the information of a retrieval target is registered, the retrieval result list 2 on which identification information (for example, an identification ID) to take out from the population 1 is set, and the history information 3 on which a pointer to point out the identification information set on the retrieval result list 2 and the validity/invalidity of the retrieval result are set.