An ultrasonic Doppler diagnostic apparatus sends ultrasonic waves to a specimen, receives a reflection signal of the ultrasonic waves from the specimen to detect a Doppler signal, obtains blood flow information indicating a peak flow velocity of coronary blood flow, and displays the flow velocity information before and after the administration of a drug to the specimen on a display unit. Then, at least velocity ranges of the flow velocity information before and after the administration of the drug to the specimen are adjusted, and during an ultrasonic scan of the specimen, data on a plurality of acquired images having different velocity ranges are adjusted to the same velocity range. A system control unit displays the data on the plurality of images adjusted to the same velocity range on the display unit.