A displacement measurement apparatus includes an ultrasound sensor transmitting ultrasounds to an object in accordance with a drive signal, and detecting ultrasound echo signals generated in the object to output echo signals a driving and processing unit supplying the drive signal to the sensor, and processing the echo signals from the sensor to obtain ultrasound echo data and a controller controlling the driving and processing unit to yield an ultrasound echo data frame at each of plural different temporal phases based on the ultrasound echo data obtained by scanning the object. The ultrasound echo data has one of local single octant spectra, local single quadrant spectra, and local single half-band-sided spectra in a frequency domain. The ultrasound echo data is obtained from plural same bandwidth spectra. A data processing unit calculates a displacement at each local position or distribution thereof in at least one of axial, lateral, and elevational directions by solving simultaneous equations derived at each local position via implementing a predetermined displacement measurement method on the ultrasound echo data yielded at the plural different temporal phases with respect to at least one of the axial, lateral, and elevational carrier frequencies and the phase, or the one of the local single octant spectra, the local single quadrant spectra, and the local single half-band-sided spectra.
