1. A video decoding method, the method comprising: receiving information on a picture corresponding to a decoding target block; entropy-decoding the information on the picture; determining a transform skip mode (TSM) for the decoding target block among a plurality of TSM candidates based on the entropy-decoded information on the picture; and inverse-transforming the decoding target block based on the determined TSM, wherein the TSM candidates comprise at least one of a 2-directional (2D) transform mode of performing both horizontal transform and vertical transform, a horizontal transform mode of performing horizontal transform, a vertical transform mode of performing vertical transform and a non-transform mode of not performing transform.