To provide an ultrasonic diagnostic instrument which enables a correction of transmission drive signals applied to a vibration element.

Each branched output line of each linear amplifier 34 is connected to an attenuator 46. A plurality of the transmission drive signals attenuated at the attenuator 46 are input into a signal selector 48. The signal selector 48 is a circuit where one of the plurality of transmission drive signals after the attenuation is selected and is passed. The selected transmission drive signal after the attenuation is converted into a digital signal at an A/D converter 50. A waveform data comparison part 54 corrects the transmission drive signals applied to each vibration element 12a by analyzing the waveform of the transmission drive signals form the comparison between the digital signals outputted from the A/D convertor 50 and an ideal waveform data stored in an ideal waveform memory 52. An amplitude voltage, the amount of delay, and the shape of the waveform are evaluated for the analysis.