PURPOSE: To compare data to the last one by skipping the data, and next, setting arbitrary locations to be compared, and further, continuing the comparison of the data.

CONSTITUTION: On the display screen of a display 100, the data in data files A and B and the comparison result of both data, etc., are displayed, and an conversational data comparison program 300' in a processor 300 performs the comparison of the data and the processing of the skip of the data, etc., according to an inputted command. When the start of comparison is indicated, the data is taken out from each data file and is compared one by one, and when noncoincidence is generated in both data, the comparison is interrupted at that time, and the fact of the noncoincidence of both data is informed to a user by displaying. The user skips the location from the one where noncoincidence is generated to the one to be compared by a large distance by using a prepared command, and continues the comparison again from the location. In such a way, the data can be compared to the last one.