2. An information associating apparatus according to claim 1 wherein: said query extraction unit extracts the search time for each search user and said query from queries used for searching during said extracted past predetermined time interval, said preprocessing unit calculating for each of said search users the minimal time interval which is the smallest value among the time intervals between the time one query was used among said plurality of extracted queries and the time a different query was used among said plurality of extracted queries, and said association degree calculation unit calculates for each of said predetermined search users the association degree between said one query and said different query according to said minimum time interval based on said smallest time interval among the predetermined search users, and calculates the interval association degree for key words by adding the degree of association calculated for said plurality of search users.
4. An information associating apparatus according to claim 2 wherein: said association degree calculation unit carries out further processing in which two key words according to one interval association degree and two key words according to another interval association degree are compiled into one group if the one key word among the two key words according to said one particular interval association degree and another key word according to another of said particular interval association degrees are identical when, after calculating the interval association degree of said key words, a plurality of particular interval degree association degrees exist in which said interval association degrees are equal to or greater then a particular interval association degree.