The present invention aims to provide image processing device and method capable of generating a difference image at high speed without occurring misregistration. To achieve this, in the image processing device and method, plural regions of interest are set respectively to input first and second images, a shift vector indicating a misregistration amount between the first and second images is calculated with respect to each of the regions of interest, a filter process is executed to the shift vector, the filter-processed shift vector is interpolated, the first and second images are registered based on the interpolated shift vector, and a subtraction operation is executed between corresponding pixels on the respective registered images to acquire the difference image.