In order to simplify a manufacturing process and reduce cost and power consumption by providing an ultrasonic diagnostic apparatus including a carrier signal generating circuit excellent in IC implementation, a carrier signal generating circuit for generating an output voltage Vo applied to an ultrasonic probe 41 includes cascaded source follower type NMOSFETs 11 to 14, a variable current source 31, and a constant current source for biasing 32. The probe 41 can be made to generate the output voltage Vo with arbitrary amplitude by controlling a gate voltage V4 by controlling the output current value of the variable current source 31. In addition, a voltage applied to each NMOSFET can be divided by connecting the NMOSFETs 11 to 14 in a multi-stage manner. Accordingly, the withstand voltage of the NMOSFET may be low.
