To provide an image processing device capable of extracting only the target object.

This image processing device is provided with a background brightness calculating means for calculating the background brightness of an input image, and a black target determining means for determining whether a black target exists on the input image; further a binarization means is provided with a means for executing the binarization corresponding to a target size, on the basis of a first threshold candidate of the input image; a second threshold candidate, on the basis of a reduced image; and a result of the determination of the black target, and only the desired target object can be executed according to the target size.