An apparatus includes: an analysis unit that analyzes a frequency of a signal generated based on an electric echo signal obtained from an ultrasound echo, the ultrasound echo being generated from ultrasound irradiated onto an observation target and reflected from the observation target, thereby calculating frequency spectra； an approximation unit that calculates features of the frequency spectra； a correction unit that performs attenuation correction for eliminating an effect of ultrasound attenuation on each of the features of the frequency spectra, using each of attenuation rate candidate values giving different attenuation characteristics when the ultrasound propagates through the observation target, thereby calculating corrected features of the frequency spectra； a setting unit that sets an optimum attenuation rate for the observation target from among the attenuation rate candidate values, using the corrected features； and a generation unit that generates feature image data based on the corrected features, using the optimum attenuation rate.
