To satisfactorily use a dictionary function even during execution of a document display function.

Strokes written in an input means 2 are detected by a stroke discrimination part 6, and their position information and data from a document memory are supplied to a character string discrimination part 7, and the word of an indicated character string and its position are discriminated. This discriminated word is supplied to a dictionary management part 8, and information of the discriminated position is supplied to an operation menu display part 9, and a signal from a picture memory 10 is supplied to a display driving part 3, and a menu picture showing the operation items is displayed on a display means 1 correspondingly to the indicated character string. When item 'dictionary' on the display is depressed, a dictionary 11 is retrieved in accordance with the word supplied to the dictionary management part 8, and this data is supplied to the display driving circuit 3 through a dictionary item display part 12. Thus, the dictionary item of the retrieval result is inserted to the picture for display of the dictionary item from the picture memory 10 and is displayed in a window on the display means 1.