Range of the object of search is specified without specific designation by the user. In case changing of the image is instructed by an image operation portion, an image changing portion changes the image and displays such image on an image display portion, and the displayed image is held in a scope holding portion as the range of the object of search. The operation from a map operation portion also is similarly processed, whereby the range of the document constituting the object of search can be specified without specific designation by the user.