An image motion sensing method applicable for an image sensing device includes the steps of capturing a plurality of sensing frames, each sensing frame including image position information of an image; selecting a base frame from the sensing frames and a sampling frame disposed after the base frame; comparing image position information of images in the base frame and the sampling frame within a base comparison range of the base frame and a sampling comparison range of the sampling frame to generate displacement information; determining a comparison range size according to the displacement information; updating sampling comparison range according to the comparison range size; selecting a sensing frame after the sampling frame as an updated sampling frame; updating the base comparison range of the base frame according to the comparison range size; and returning to the foregoing step of comparing the image position information.