A printing device, comprising: a receiving means (104, 106, 108) configured to receive image data; a printing means configured to transfer printing agent onto a sheet _(P, PA) so as to form an image according to the image data received by the receiving means (104, 106, 108); a printing ratio determining means configured to determine, based upon the image data, a printing ratio that is a ratio of an area to be filled with the printing agent on the sheet (P, PA) to a whole area of the sheet (P, PA); a first determining means configured to determine whether the printing ratio determined by the printing ratio determining means is equal to or more than a first predetermined value that is a printing ratio at less than which the sheet (P, PA) is classified into a recyclable sheet (P, PA) when the printing agent is transferred onto the sheet P, PA); and a control means configured to control the printing means to transfer the printing agent onto the sheet (P, PA) depending on the determination made by the first determining means, wherein the control means includes a reduction ratio determining means configured to determine a reduction ratio to attain a printing ratio less than the first predetermined value when the first determining means determines that the determined printing ratio is equal to or more than the first predetermined value, the reduction ratio being a ratio of an area of a reduced image of an original image according to the image data to an area of the original image, characterized in that the control means controls the printing means to print, on the sheet (P, PA), the reduced image formed by reducing the original image at the reduction ratio determined by the reduction ratio determining means, and the reduced image is formed by reducing an area of each pixel included in the original image. a receiving means (104, 106, 108) configured to receive image data; a printing means configured to transfer printing agent onto a sheet _(P, PA) so as to form an image according to the image data received by the receiving means (104, 106, 108); a printing ratio determining means configured to determine, based upon the image data, a printing ratio that is a ratio of an area to be filled with the printing agent on the sheet (P, PA) to a whole area of the sheet (P, PA); a first determining means configured to determine whether the printing ratio determined by the printing ratio determining means is equal to or more than a first predetermined value that is a printing ratio at less than which the sheet (P, PA) is classified into a recyclable sheet (P, PA) when the printing agent is transferred onto the sheet P, PA); and a control means configured to control the printing means to transfer the printing agent onto the sheet (P, PA) depending on the determination made by the first determining means, wherein the control means includes a reduction ratio determining means configured to determine a reduction ratio to attain a printing ratio less than the first predetermined value when the first determining means determines that the determined printing ratio is equal to or more than the first predetermined value, the reduction ratio being a ratio of an area of a reduced image of an original image according to the image data to an area of the original image, characterized in that the control means controls the printing means to print, on the sheet (P, PA), the reduced image formed by reducing the original image at the reduction ratio determined by the reduction ratio determining means, and the reduced image is formed by reducing an area of each pixel included in the original image.