Provided is an ultrasound imaging apparatus that is cable of estimating a three-dimensional effect of a blood flow, by using blood-flow velocity information obtained by a color Doppler method, and presenting diagnostic information into which the three-dimensional effect is reflected. The ultrasound imaging apparatus of the present invention is provided with an ultrasound probe configured to transmit ultrasound waves to a test object and to receive echo signals reflected from the test object, and a signal processor configured to process the echo signals received by the ultrasound probe, and the signal processor estimates the three-dimensional effect of the blood flow velocity, from a difference between a first blood flow velocity estimated from the echo signals by a first method, and a second blood flow velocity estimated by a second method which is different from the first method, and generates diagnostic information into which the three-dimensional effect is reflected.
