A Doppler waveform generation unit 30 obtains Doppler information from a reception signal collected from a diagnosis region and generates a Doppler waveform. An initial time-phase setting unit 40 sets a beginning initial time-phase and an ending initial time-phase of the Doppler waveform. In the setting, an electrocardiographic waveform signal obtained from a subject using an electrocardiograph or the like and learned data stored in a learned data storage unit 60 are used. A measurement time-phase search unit 50 searches for a beginning time-phase of the Doppler waveform near the beginning initial time-phase, and searches for an ending time-phase of the Doppler waveform near the ending initial time-phase. In the search process, the learned data stored in the learned data storage unit 60 is used.
