1. An apparatus for code obfuscation, comprising: an input unit that receives execution codes for android applications; a code analyzer that separates the input execution codes into sensitive codes that needs to be protected from application forgery attack and general codes except for the sensitive codes by analyzing the input execution codes; a dalvik to C code converter that creates native codes by converting the sensitive codes into a C code; an obfuscator that obfuscates the native codes and the general codes; a self code protector that encrypts the obfuscated native codes by adding a tamper-detection code to the obfuscated native codes and then creates self-modified native codes by adding a loading routine; and a code combiner that combines the self-modified native codes with the obfuscated general codes.