Disclosed are an intra-prediction method using filtering and an apparatus using the method. An image-decoding method comprises: a step of filtering an n upper reference pixel of a block to be predicted and neighboring pixels of the n upper reference pixel so as to obtain the filtered n upper reference pixel; and a step of filtering an n left reference pixel of a block to be predicted and neighboring pixels of the n left reference pixel so as to obtain the filtered n left reference pixel. According to the present invention, intra-prediction may be efficiently performed to improve image-encoding/decoding efficiency.