There is provided a technique for obtaining a high-quality image by extracting only a nonlinear component with high accuracy in ultrasonic imaging using an amplitude modulation method of THI. By removing a fundamental wave component with high accuracy by making the influence of electrical distortion due to analog amplification on the echo signals of ultrasonic waves having different sound pressure levels approximately the same, only the nonlinear component is extracted with high accuracy. For example, the above influence is made to be the same by controlling the amplification factor of an amplification section. In addition, the above influence is made to be the same by restoring the digital data with a filter.
