Disclosed is a video signal processing method comprising the steps of: obtaining at least one transform block for a residual signal of a current block from a video signal bitstream; determining, on the basis of length information of a first side of the transform block, a horizontal transform kernel for horizontal transformation of the transform block, regardless of the length of a second side of the transform block, which is orthogonal to the first side; determining, on the basis of length information of the second side, a vertical transform kernel for vertical transformation of the transform block, regardless of the length of the first side; obtaining the residual signal of the current block by performing, on the transform block, inverse transformation using the horizontal transform kernel and the vertical transform kernel; and reconstructing the current block on the basis of the obtained residual signal.