Provided are a method and apparatus for performing transformation and inverse transformation on a chroma block by using a variable transform kernel, during video encoding and decoding processes. A video decoding method includes: obtaining, from a bitstream, chroma multi-transform kernel information indicating whether a chroma transform kernel for inverse transformation of a chroma block is determined to be among a plurality of chroma transform kernels; while determining whether the chroma transform kernel is determined to be among the plurality of chroma transform kernels according to the chroma multi-transform kernel information, determining whether to determine the chroma transform kernel by using a luma transform kernel; and performing inverse transformation on the chroma block by using the chroma transform kernel.