An apparatus for encoding an information bit stream using turbo code is provided. The apparatus includes a temporary bit generator for creating a temporary bit stream, an interleaver for independently receiving the information bit stream and the temporary bit stream, a first constituent encoder for independently receiving the information bit stream and the temporary bit stream and generating a first parity bit stream and a second constituent encoder for receiving an output of the interleaver and generating a second parity bit stream. Performance of a turbo code can be enhanced without changing a code rate by making a decoded bit stream longer.