To provide a technique by which the paramter of a characteristic model can be extracted with good efficiency.

The parameter of a characteristic model is extracted in such a way that the minimum value of an error function S is found. First, an enumeration technique by which, while a probability that the parameter is updated so as to increase the error function S is kept to be positive, the parameter is updated is executed in Step 121. As the convergence condition of the enumeration technique, whether the error function S is decreased or not between t pieces of continuous states is judged in Step 122b. When YES is judged in Step 122b, this procedure proceeds to Step 123, and A Newton's method-based solution method in which the parameter is updated so as to reduce the error function S is executed.