When an additional search key of an input unit is operated by the user, if a current display on a display screen of a display unit is a list display of respective example sentences, a user input for refining example sentences is received, and example sentences are refined in accordance therewith. When the additional search key is operated by the user, if the current display is a display of explanatory information on the vocabulary entry, the display screen of the display unit is split into two, and a search of the explanatory information is carried out on one split screen.