PURPOSE: To implement the simulation in which an error in a logic circuit design is analyzed efficiently.

CONSTITUTION: A data system/control system signal discrimination means 1 receiving logic circuit information 101 divides the input signal into a data system signal and a control system signal. A numeral is set to the control system signal and input value symbol cross reference information 105 is generated. A simulation means 3 implements simulation while symbols and numerals are in existence in mixture, and a simulation result display means 4 displays the result without modification when the equation of simulation result is short, obtains the symbol in the equation from the input value symbol cross reference information 105 and makes calculation and displays the result in numerals.