PURPOSE: To obtain an easily observable and satisfactory image by preventing an interference between transmitting and receiving signals and eliminating a speckle pattern generated on an ultrasonic image.

CONSTITUTION: A transmitting pulse signal generated by a transmission control circuit 13 is amplified by a transmitting amplifier 11 and sent out to an ultrasonic vibrator 2, and by driving the ultrasonic vibrator 2, an ultrasonic wave is transmitted to an examinee body. Subsequently, a receiving signal from the examinee body, received by the ultrasonic vibrator, 2 is amplified by a receiving amplifier 12, subjected to A/D conversion by an A/D converter 14 and stored in a prescribed address of an image memory 17, and by reading out image data from the image memory 17, an ultrasonic tomographic image is generated. In this case, by changing a phase of the transmitting pulse signal or the receiving signal at every scanning line by a timing control circuit 15, an interference between transmitting and receiving signals is eliminated.