PURPOSE: To provide the method and device for automatically displaying the conditions of decreasing idle memory areas by the increase of records in a data base.

CONSTITUTION: The memory area of the data base is divided into blocks for the unit of prescribed memory capacity, and all the blocks for the information of one bit showing whether each divided block is used or not is stored in a prescribed bit map area. Then, the number of used blocks in the bit map is summed up in a prescribed cycle and stored in a data base capacity summary file 5 together with the date. The data base capacity summary file 5 is read in a prescribed cycle, percentage for the number of used blocks is calculated in the order of the date, and a data base storage rate history list 7 is outputted as the list of use conditions. The use conditions can be automatically recognized by this data base storage rate history list 7, and the data base can be maintained without being delayed.