1. An ultrasonic diagnosis apparatus comprising: an ultrasonic probe; a transmission/reception unit configured to transmit an ultrasonic wave to a subject via the ultrasonic probe and receive an echo signal corresponding to an ultrasonic wave reflected by the subject; a first volume data generating unit configured to generate first volume data based on the received echo signal; a low-frequency/high-frequency volume data generating unit configured to generate low-frequency volume data and high-frequency volume data on spatial frequencies based on the generated first volume data; a filter unit configured to calculate three eigenvalues for classifying three-dimensional structure patterns of three-dimensional structures contained in the generated low-frequency volume data, calculate edge information based on two eigenvalues of the three eigenvalues, and apply a nonlinear anisotropic diffusion filter having a filter characteristic corresponding to the calculated edge information to the low-frequency volume data; a high-frequency voxel control unit configured to perform edge enhancement processing for the high-frequency volume data based on the generated edge information; and a second volume data generating unit configured to generate second volume data with reduced speckle and reduced noise based on the low-frequency volume data to which the nonlinear anisotropic diffusion filter is applied by the filter unit and the high-frequency volume data for which edge enhancement processing is performed by the high-frequency voxel control unit.