1. An obfuscation method for obfuscating a program using a processor, said obfuscation method comprising: an obfuscation step of generating, using the processor, an obfuscated code by obfuscating original code of the program; a first execution step of executing the obfuscated code generated in said obfuscation step; a first logging step of generating first logging data by logging execution details of said first execution step; an evaluation step of evaluating the first logging data, thereby identifying a degree of obfuscation of the obfuscated code; and a re-obfuscation step of re-obfuscating the original code based on a result of the evaluation performed in said evaluation step.