A video encoding/decoding apparatus, a deblocking filter and filtering method based on intra-prediction directions for same, and recording media are disclosed, and the deblocking filter includes: a boundary strength determiner for determining strength of boundary of current block; an intra-block identifier for confirming intra-block identity of a subblock enclosing first pixel at a certain location with reference to the boundary; an intra-prediction direction identifier for identifying an intra-prediction direction of the subblock if the subblock is identified as an intra-block; a filtering pixel selection unit for selecting pixels for filtering based on the first pixel and the identified intra-prediction direction; and a filtering unit for filtering in horizontal direction, vertical direction, or diagonal direction depending on the intra-prediction direction and relationships between pixel values of the selected pixels to eliminate deblocking artifacts within diagonal edges at a boundary between blocks by deblocking filtering in the intra-prediction direction.