RETRIEVAL DEVICE

PROBLEM TO BE SOLVED: To eliminate such a possibility that an unnecessary explanatory sentence is displayed double. SOLUTION: When a processing is started, an index word of an electronic book is acquired in a step (1), it is judged in a step (2) whether or not the index word is found, and the index work is compared with an inputted character string in a step (3). When the match each other (YES), it is judged in a step (4) whether or not the input character string contains one of numbers '0' to '4' showing a tone and when (YES), only an index word containing an English letter and a number is read in a step (5), but when not (NO), only the index word containing only the English is read in a step (7). Then the index word which is read in is stored in a step (6). Further, when no index word is found in the step (2), the retrieving if completed in a step (8), and the index word stored in the step (9) and the explanatory sentence paired with the index word are displayed.