An ultrasound diagnostic apparatus, comprising: an ultrasound probe ; a transmission and reception unit that transmits an ultrasound beam from the ultrasound probe toward a subject, receives an ultrasound beam reflected from the subject, and processes a received signal output from the ultrasound probe to generate received data; a complex data generation unit that generates first complex data including amplitude information and phase information by orthogonally detecting the received data generated by the transmission and reception unit using a first center frequency (C1) and a first cutoff frequency (F1) and generates second complex data by orthogonally detecting the same data as the received data using a second cutoff frequency (F2) and a second center frequency (C2) lower than the first center frequency; a B-mode processing unit that generates a B-mode image using amplitude information of at least one of the first complex data or the second complex data; a phase difference calculation unit that calculates a first phase difference (θ1) between frames using phase information of the first complex data and calculates a second phase difference (θ2) between frames using phase information of the second complex data; a phase difference correction unit that corrects the first phase difference for an entire measurement target tissue of the subject using the second phase difference calculated by the phase difference calculation unit from only phase information of the second complex data at a representative point of the measurement target tissue of the subject; and a displacement amount calculation unit that calculates an amount of displacement of the measurement target tissue of the subject using the corrected first phase difference. an ultrasound probe ; a transmission and reception unit that transmits an ultrasound beam from the ultrasound probe toward a subject, receives an ultrasound beam reflected from the subject, and processes a received signal output from the ultrasound probe to generate received data; a complex data generation unit that generates first complex data including amplitude information and phase information by orthogonally detecting the received data generated by the transmission and reception unit using a first center frequency (C1) and a first cutoff frequency (F1) and generates second complex data by orthogonally detecting the same data as the received data using a second cutoff frequency (F2) and a second center frequency (C2) lower than the first center frequency; a B-mode processing unit that generates a B-mode image using amplitude information of at least one of the first complex data or the second complex data; a phase difference calculation unit that calculates a first phase difference (θ1) between frames using phase information of the first complex data and calculates a second phase difference (θ2) between frames using phase information of the second complex data; a phase difference correction unit that corrects the first phase difference for an entire measurement target tissue of the subject using the second phase difference calculated by the phase difference calculation unit from only phase information of the second complex data at a representative point of the measurement target tissue of the subject; and a displacement amount calculation unit that calculates an amount of displacement of the measurement target tissue of the subject using the corrected first phase difference. <EOS>