It is an object to provide a parameter extraction method using a model equation having a physical meaning, in which parameters optimum for an element are extracted without setting appropriate initial values based on experience or deep understanding of models and actual device characteristics.A structure is provided in which multiple patterns of initial values of parameters are generated by a random number generator mechanism, and automatic parameter extraction is executed for each initial value to select a combination of parameters in which ultimate difference between a calculated value and a measured value is minimized thereby finding an optimal solution.