A technology for providing a small and inexpensive ultrasonic diagnostic apparatus which does not need a high resolution A/D converter, and has high sensitivity and a wide dynamic range is disclosed. According to the technology, an ultrasonic transducer unit 1 for transmitting and receiving ultrasonic wave is driven by a drive circuit 2 for generating a pulse signal. An echo signal received by the ultrasonic transducer unit is inputted to an analog low frequency band attenuator 3 which attenuates a low frequency band component. An output signal of the analog low frequency band attenuator is inputted to an A/D converter 4 which converts the signal to a digital signal. The converted and outputted digital signal is inputted to a digital correction filter 5 which intensifies the low frequency band component attenuated by the analog low frequency band attenuator and outputs a digital signal having a frequency distribution almost equal to that of the echo signal received by the ultrasonic transducer unit.