To carry out circuit simulation by using a statistically created current model based on the operation rate of a circuit, and to analyze a spectrum included in a current waveform in a short time.

In a partial circuit operation current analyzing part 10, the current waveform of a partial circuit is integrated into a database (DB), and the current waveform is created by a current waveform shaping part 50 from the operation rate of the partial circuit obtained from a high speed simulator in a circuit operation rate analyzing part 20 and the operation of the partial circuit integrated into the DB, and simulation is carried out two or more times by a circuit simulation part 60. Thus, it is possible to quickly obtain the fluctuation of the current waveform, and to efficiently carry out the spectrum analysis of a signal by a spectrum analyzing part 70.