An ultrasonic imaging apparatus includes a probe that transmits an ultrasonic pulse to an object to be detected and receives a reflection ultrasonic pulse train from the object to be detected, a sound pressure amplitude control device for automatically changing, with one frame including a repetition of the transmission and the reception which acquires a piece of tomographic image information of the object to be detected as a minimum change unit, a sound amplitude of the ultrasonic pulse according to an acquisition number of a frame indicative of an order of the acquisition, and a display unit that displays the tomographic image information.