PURPOSE: To enable an operator to interactively input a condition and to automatically select and execute necessary analysis under the inputted condition by displaying a characteristic graph display frame on a display screen and displaying plural input menues for determining conditions on the horizontal and vertical axes of the characteristic graphic.

CONSTITUTION: A setting condition name is inputted on the horizontal axis of a characteristic graph frame 2 displayed on a display frame 1 by means of a condition input menu. The maximum and minimum value menues of respective conditions are inputted. After inputting data by respective menues, the condition name of the horizontal axis is decided by inspection processing and DC analysis, AC analysis or transient analysis is executed in accordance with the setting of voltage, frequency or time. The analytical condition input and a result output condition setting menu are set up correspondingly to the conditions of the horizontal and vertical axes of the characteristic graph. Since the constitution can automatically select required analysis from the input condition of each menu, the analysis necessary for obtaining the characteristic graph can be accurately executed and the electronic circuit simulation system can be obtained by the simple work.