An image processing system of the present invention comprises an image inputting portion 1 for inputting image data, a ground-level detecting portion 3 for detecting a ground level of the input image data, a pasted-manuscript deciding portion 4 for deciding whether or not the image data is a pasted manuscript, based on a user's indication or the ground level detected by the ground-level detecting portion 3, a ground-level adjusting portion 5 for adjusting the ground level in response to a distribution of the ground level detected by the ground-level detecting portion 3 if the image data is decided as the pasted manuscript, and a ground removal processing portion 6 for removing a ground of the image data at the ground level adjusted by the ground-level adjusting portion 5.