Abstract: Disclosed is an adaptive intra-prediction encoding and decoding method. The adaptive intra-prediction encoding method comprises the following steps: providing a prediction unit to be encoded; determining the total number of prediction modes for intra-prediction in accordance with the size of the prediction unit; selecting a certain prediction mode on the basis of the displacement of a reference pixel among the determined total number of the prediction modes, and performing intra-prediction using the selected prediction mode; and transforming and quantizing the residual value, which is the difference between the prediction unit predicted by the intra-prediction and the current prediction unit, and entropy-encoding the transformed and quantized value. Thus, rate-distortion may be optimized and image quality and encoding speed may be improved.