Abstract: There are provided an apparatus and method for detecting an executable code, capable of verifying reliability of an extracted signature by determining whether there is present an executable code in network data by using instruction pattern information related calling mechanism of function for distinguishing the executable code from a non-executable code, the method including: forming instructions by reverse assembling network data suspicious as an attack; comparing the respective formed instructions with instruction patterns according to calling mechanism of function; and determining whether there is present an executable code in the network data according to a result of the comparing