To obtain a parameter creation method of a large signal equivalent circuit model of a relatively simple GaAs FET, which can show characteristics such as PHEMT accurately even if a bias voltage is changed, and to provide a simulation method of a circuit that performs large signal operation using the PHEMT.

For the parameter creation method of the large signal equivalent circuit model of a GaAs FET, in a variable V1 of a numerical expression for indicating a drain current Ids of a Curtis Etenberg model that is the large signal equivalent circuit model for expressing the electric characteristics of FETs, a numerical expression is applied. In the numerical expression, the term of a gate voltage is not applied to the value of δ that is a correction term of Ids-Vgs characteristics in the case of a value that differs from Vds when parameters are extracted.