Provided are a method of and an system for coding a grouped zerotree wavelet image having high coding efficiency regardless of the scale of a wavelet transform. According to an embodiment of the present invention, a method of coding an input image to a bitstream by using a zerotree wavelet transform, the method comprises merging a plurality of adjacent zerotrees, and coding the merged zerotrees to one symbol and outputting the symbol. The method further comprises transforming the input image to a wavelet domain having a plurality of wavelet coefficients via the zerotree wavelet transform, and generating the plurality of adjacent zerotrees each having the plurality of wavelet coefficients.