Methods and apparatuses for encoding and decoding a residual block are provided. The method of encoding the residual block includes: generating a prediction block of a current block; generating a residual block based on a difference between the prediction block and the current block; generating a transformation residual block by transforming the residual block to a frequency domain; splitting the transformation residual block into frequency band units; and encoding effective coefficient flags indicating frequency band units, of the frequency band units, in which nonzero effective transformation coefficients exist.