PURPOSE: To easily compare many groups of data which are distributed in the same area on a two-dimensional coordinate plane, among the groups and in the groups.

CONSTITUTION: A data storage part 40 is stored with many data. A data retrieval part 11 reads (m) groups of (n) data corresponding to (n) specific two-dimensional coordinate values out of the storage part 40 according to a retrieval key from a data command input part 20. A coordinate conversion part 12 converts the (m) groups of two-dimensional coordinate data into data corresponding to linear coordinate values, group by group, according to a conversion rule from the data command input part 20. A graph data generation part 13 makes the names of the respective groups of data correspond to the X axis of the two-dimensional coordinate system, the linear coordinate values corresponding to the two-dimensional coordinate values correspond to the Y axis, and data value correspond to the Z axis to generate m×n three-dimensional graph data, which are displayed at a display part 30.