The disclosure presents a quilting data processing apparatus and a program capable of displaying changes of fabric caused by a sewing line, and or easily displaying a visual image of a finished state of quilting. The CPU receives the fabric pattern of quilting, the thickness of fabric, the thickness of elastic material, and the sewing line of quilting, and, when the preview button is pressed, creates a basic mesh pattern, calculates the total deformation degree, deforms the basic mesh pattern sequentially along the sewing line to a deformation degree commensurate with the total deformation degree, and deforms each mesh adjacent to deformed meshes commensurately with the deformation degree, thereby creating a deformation mesh pattern (S1 to S5). Consequently, the CPU adheres to each mesh the fabric pattern displayed in a specified size in accordance with the deformation mesh pattern so as to create deformation fabric image data, overlaps the sewing line data to the upper side of the deformation fabric image data, and displays as a quilting pattern (S6 to S7).