The present invention discloses a method and an apparatus for acquiring motion information. A frequency domain transformation is performed on a detection signal of a vibration propagating in a medium to obtain a frequency domain signal, then a signal that is outside of a defined vibration velocity range is removed from the frequency domain signal, that is, only a vibration signal is retained, and then a position-time diagram is obtained along a defined vibration propagation direction. It is not necessary to perform motion estimation on propagation of the vibration by a complicated calculation, and it is only necessary to determine the presence or absence of the vibration by processing in the frequency domain, and then the position-time diagram is obtained, which is a highly efficient method for acquiring motion information.
