1. A simulation apparatus for executing simulation for performance evaluation of a system to be implemented by software and hardware using a hardware model, comprising: a first acquisition section adapted to execute existing tentative software to acquire a first execution log; a division section adapted to divide the first execution log into a plurality of basic processing units; a basic processing execution log production section adapted to modify some of the plural basic processing units to produce a basic processing execution log to be used for the simulation; and a simulation execution section adapted to input the basic processing execution log to the hardware model to execute the simulation to acquire information required for the performance evaluation.