PURPOSE: To quickly retrieve a desired data item by using a word information table where the words forming data items and the keys added to these words are previously stored and a data item information table where the data items corresponding to those keys are previously stored.

CONSTITUTION: The words forming the data items and the keys added to these keys are previously stored in a word information table 4. At the same time, the data items corresponding to those keys are previously stored in a data item information table 5. A data item retrieving mechanism part 6 searches a key 5-1 of a relevant word out of the table 4 based on the informed words forming the data item to be retrieved and takes out the data item corresponding to the key 5-1 for output.