PURPOSE: To efficiently retrieve required information from a many pieces of information by enabling plural kinds of classification of a retrieval target to be selected from the display screen of the hierarchical structure of the whole classification in which information in a data base is hierarchically classified.

CONSTITUTION: This retriever is constituted in such a way that a retrieval condition is inputted from a classification menu selection part or a retrieval character string input part to an information retrieval part, and the information corresponding to the retrieval condition is read out from a data base part by the information retrieval part, and a retrieval result is displayed on the screen of a display part. In such a case, an information retriever in which the information in the data base is hierarchically classified and the whole classification is hierarchically displayed is constituted so that the plural kinds of classification in arbitrary hierarchies can be selected from the whole classification (A-1), (B-1). (B-2), (B-3)..., as targets to be retrieved. In other words, the plural kinds of classification can be selected from the whole classification as the retrieval targets, and also, the information corresponding to a retrieval character string can be retrieved for each of selected whole classification, respectively.