1. An image decoding apparatus comprising: a parsing module for decoding intra prediction information from a received bit stream; an intra prediction mode decoding module for decoding an intra prediction mode of a current prediction unit using the intra prediction information; and a prediction block creating module for creating a prediction block using the intra prediction mode, wherein the intra prediction information includes a prediction mode group indicator and a prediction mode index, and the decoding method of the prediction mode index varies depending on the prediction mode group indicator.