A method of ultrasonic diagnostics, wherein, while a detector including an encoder that oscillates with an oscillation of an ultrasonic element unit is caused to output at least a single-phase rotary encoder pulse signal as an angle signal (S1, S3) so as to detect an oscillation angle of the ultrasonic element unit based on the angle signal (S1, S3), the ultrasonic element unit is caused to perform ultrasonic wave scanning. The method comprises: the detector outputting the angle signal (S1, S3), and outputting an origin-return signal (S2) that shows different logic levels depending on whether the ultrasonic element unit is located in a positive region or a negative region, the positive region and the negative region being divided at an oscillation origin performing a control of origin return in which the ultrasonic element unit is caused to oscillate in a direction determined by the origin-return signal (S2) while being caused to detect an origin-return signal at each oscillation position, so that the ultrasonic element unit is caused to oscillate to a changing point of the logic level of the origin-return signal (S2) and after the control of origin return, causing the ultrasonic element unit to perform ultrasonic wave scanning, while causing the detector to detect an oscillation angle of the ultrasonic element unit on the basis of the angle signal (S1, S3).
