The present disclosure provides an ultrasound imaging apparatus. The ultrasound imaging apparatus includes an ultrasonic probe for transmitting an ultrasound signal toward an object, receiving an echo ultrasound signal reflected from the object, and transforming the echo ultrasound signal to an electric signal; a beamformer for beamforming and outputting the electric signal; an image reconstruction unit for generating a reconstructed image by applying a Point Spread Function (PSF) to an ultrasonic image corresponding to the output signal; and an image post-processor for performing filtering to emphasize a peak point of the reconstructed image. The use of a filter to emphasize a peak point may facilitate an accurate setting of a phase parameter to be used in estimation of a PSF. Accordingly, an almost ideal PSF may be estimated, image reconstruction is performed using the estimated PSF, and thus a high resolution image may be obtained.