An encryption apparatus capable of effectively preventing encryption data from being illegally generated is provided. Based on apparatus identification data of an IC, which is input from a computer, a secure application module (SAM) selects an encryption method from among a plurality of different encryption methods. Based on the code of the IC, the SAM selects plaintext data to be encrypted from among the plurality of different pieces of plaintext data. The SAM outputs encryption data such that the selected plaintext data is encrypted by the selected encryption method.