1. A terminal device comprising: an annotation database which accumulates a plurality of annotation rules created for each window in which an annotation text is to be displayed; a business screen state acquisition section which always monitors which of windows displayed on an operation screen on which a plurality of windows can be displayed is an active window and requests, when through searching of the annotation database an annotation rule corresponding to the active window exists in the annotation database and annotation display operation is performed by the user, an annotation display section to display an annotation text; and the annotation display section which obtains an annotation rule associated with user's operation from the annotation database in response to the request from the business screen state acquisition section and displays an annotation text included in the annotation rule on the operation screen.