Recently in the field of computer vision, there have been many attempts to obtain a symbolic shape description of a 3D object by fitting simple primitives to the range data. Since many of these researches required to solve nonlinear minimization problems, they cost so much time and it was difficult to obtain a unique shape description for the given range data. This paper proposes a method to obtain a unique shape description of an object by using wavelet transforms. Wavelet transform is a new technique for signal analysis which decompose a signal on locally distributed orthonormal basis functions. We first decompose a volume data on 3D wavelet basises and then approximate the shape with a relatively small number of functions by using only significant basis functions. We have successfully applied this method to a human head volume data and typical results are shown.