To execute change-over into focus data corresponding to a probe only by taking up the probe which an operator wants to use.

An ultrasonograph is provided with a magnetic disk 12 storing focus data of a ultrasonic beam for every kind of probes 3-6, sensors 14-16 detecting the probe which is selected by the operator and a focus memory part 11 reading focus data of the probe selected by the operator from the magnetic disk 12 based on the outputs of the sensors 14-16 and storing it. Then, focus data read from the magnetic disk 12 to the focus memory part 11 is supplied to the selected probe so that ultrasonic wave transmission and reception are executed.