An ultrasound imaging apparatus and method in which an ultrasound signal is transmitted a plurality of times in each scanning direction and its echo is received. A Doppler signal detected from a group of echo signals consisting of a train of sequential Doppler data for each spatial sample position in each scanning direction. The amount of instantaneous changes in a phase of a clutter component included in the Doppler signal is estimated, the clutter component occurring due to reflection of the ultrasound signal from an organ. A phase of the Doppler signal is corrected using the estimated amount of instantaneous changes in the phase. A constant value corresponding to the clutter component is subtracted from the Doppler signal of which phase is corrected, information representing a blood flow is extracted based on the Doppler signal of which clutter component is removed and the extracted information is displayed in color.