Provided is an apparatus and method for varying the length of an error check code of a PDU according to the length of a payload in a broadband wireless communication system. A transmitting apparatus includes a first generator and a second generator. The first generator generates a payload of a PDU. The second generator selects the length of an error check code according to the length of the generated payload, generates an error check code according to the selected length, and suffixes the error check code to the payload.