Disclosed are a method and an apparatus, which enhance a quality of an ultrasound image to provide an improved image. An adaptive demodulation method includes acquiring input radio frequency (RF) data, quadrature-demodulating the input RF data to output an inphase-quadrature (IQ) signal, determining a valid region for the input RF data, and estimating attenuation of a frequency of the IQ signal, based on data included in the valid region among the input RF data and performing frequency compensation corresponding to the estimated attenuation of the frequency.
