A video decoding method comprising: generating a prediction block by performing intra prediction on a current block, and by performing filtering on a filtering target pixel in the prediction block; and generating a reconstructed block based on the prediction block, wherein at least one filter for the filtering is determined based on an intra prediction mode for the current block, the filtering target pixel is one of a plurality of filtering target pixels comprising one or more pixels on a left vertical prediction pixel line that is one vertical pixel line positioned at a leftmost side of the prediction block and one or more pixels on an upper horizontal prediction pixel line that is one horizontal pixel line positioned at an uppermost side of the prediction block, the filtering is performed using a 3-tap filter in a case that the filtering target pixel is a left upper prediction pixel positioned at a leftmost upper side of the prediction block and the intra prediction mode for the current block is a DC mode, the filtering is performed using a 2-tap filter in a case that the filtering target pixel is not the left upper prediction pixel and the intra prediction mode for the current block is the DC mode, the 3-tap filter has a predetermined fixed filter shape, a predetermined fixed filter tap and a plurality of predetermined fixed filter coefficients for a plurality of block sizes of the current block, the 2-tap filter has a predetermined fixed filter shape, a predetermined fixed filter tap and a plurality of predetermined fixed filter coefficients for a plurality of block sizes of the current block, the 2-tap filter is applied to the filtering target pixel based on the filtering target pixel and a reference pixel adjacent to an upper portion or a left portion of the filtering target pixel, in the 2-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel is 3/4 and a filter coefficient allocated to a filter tap corresponding to the reference pixel is 1/4 for the plurality of block sizes of the current block, the 3-tap filter is applied to the filtering target pixel based on the filtering target pixel, an upper reference pixel adjacent to an upper portion of the filtering target pixel and a left reference pixel adjacent to a left portion of the filtering target pixel, and in the 3-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel is 2/4, a filter coefficient allocated to a filter tap corresponding to the upper reference pixel is 1/4 and a filter coefficient allocated to a filter tap corresponding to the left reference pixel is 1/4 for the plurality of block sizes of the current block. generating a prediction block by performing intra prediction on a current block, and by performing filtering on a filtering target pixel in the prediction block; and generating a reconstructed block based on the prediction block, wherein at least one filter for the filtering is determined based on an intra prediction mode for the current block, the filtering target pixel is one of a plurality of filtering target pixels comprising one or more pixels on a left vertical prediction pixel line that is one vertical pixel line positioned at a leftmost side of the prediction block and one or more pixels on an upper horizontal prediction pixel line that is one horizontal pixel line positioned at an uppermost side of the prediction block, the filtering is performed using a 3-tap filter in a case that the filtering target pixel is a left upper prediction pixel positioned at a leftmost upper side of the prediction block and the intra prediction mode for the current block is a DC mode, the filtering is performed using a 2-tap filter in a case that the filtering target pixel is not the left upper prediction pixel and the intra prediction mode for the current block is the DC mode, the 3-tap filter has a predetermined fixed filter shape, a predetermined fixed filter tap and a plurality of predetermined fixed filter coefficients for a plurality of block sizes of the current block, the 2-tap filter has a predetermined fixed filter shape, a predetermined fixed filter tap and a plurality of predetermined fixed filter coefficients for a plurality of block sizes of the current block, the 2-tap filter is applied to the filtering target pixel based on the filtering target pixel and a reference pixel adjacent to an upper portion or a left portion of the filtering target pixel, in the 2-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel is 3/4 and a filter coefficient allocated to a filter tap corresponding to the reference pixel is 1/4 for the plurality of block sizes of the current block, the 3-tap filter is applied to the filtering target pixel based on the filtering target pixel, an upper reference pixel adjacent to an upper portion of the filtering target pixel and a left reference pixel adjacent to a left portion of the filtering target pixel, and in the 3-tap filter, a filter coefficient allocated to a filter tap corresponding to the filtering target pixel is 2/4, a filter coefficient allocated to a filter tap corresponding to the upper reference pixel is 1/4 and a filter coefficient allocated to a filter tap corresponding to the left reference pixel is 1/4 for the plurality of block sizes of the current block.