Provided is an ultrasound imaging apparatus which can compensate deterioration in the image quality resulting from heterogeneity of a test object medium.A reception beamformer 108 performs synthesizing after performing phasing processing of a signal received by an ultrasound element array 105 for each of two or more steering directions. The two or more steering directions are instructed by a steering direction instruction unit 112. The two or more steering directions include two directions each of which forms predetermined angles on the right and left with respect to a direction of a reception focal point along the ultrasound element array in an array direction. The predetermined angles are preferably null angles.
