A video encoding/decoding apparatus and method are disclosed. The video encoding/decoding apparatus includes: a video encoder for generating predicted subblocks by predicting subblocks into which macroblock is divided, generating residual subblocks by subtracting predicted subblocks from subblocks, generating quantized transform coefficients by transforming and quantizing residual subblocks by using transform selected according to subblock size, and generating encoded video data by using different context tables according to the macroblock and subblocks when using CABAC to encode the quantized transform coefficients; and a video decoder for reconstructing information of partition type, motion, transform type and quantized transform coefficients by decoding encoded data by using a CABAC and different context tables according to a macroblock and subblocks, reconstructing residual subblocks by inverse-quantizing/inverse-transforming the quantized transform coefficients by using a transform identified by the transform type information, generating predicted subblocks, reconstructing the subblocks, and reconstructing the macroblock based on the subblocks.