1. An image-processing device comprising: a storage unit which stores font data of each character with standard form data for each of a plurality of prescribed fonts, the font data comprising a character code specifying the character and form data representing form of the character specified by the character code; a judgment unit which judges, upon receiving a drawing instruction which comprises a character code specifying a character, font information specifying a font type, font size information specifying a font size and style information specifying whether or not to express the character in boldface type, whether each character should be expressed in boldface type or not based on the style information in the drawing instruction; a boldface data-generating unit which generates boldface form data of the character, when the judgment unit judges that the character should be expressed in boldface type, by reading out the standard form data of the character corresponding to the font type specified by the font information comprised in the drawing instruction from the storage unit, determining shift amounts in horizontal and vertical directions based on the font size information comprised in the drawing instruction, each of the shift amounts specifying horizontal shift amounts and vertical shift amounts, and repeating drawing of the standard form data by shifting the standard form data in the horizontal and vertical directions according to the determined shift amounts; and an output unit which converts the boldface form data generated by the boldface data-generating unit into image-formation data and outputs the image-formation data to an image-formation device which forms an image according to the image-formation data, wherein the boldface data-generating unit comprises a shift amount adjustment unit which adjusts the shift amounts in the horizontal and vertical directions so that result of repeating drawing of a dot of the standard form data by shifting the standard form data in the horizontal and vertical directions according to the shift amounts to draw a matrix lacks one or more dots at each of four corners of the matrix, and wherein the boldface data-generating unit generates the boldface form data by repeating the drawing of the standard form data according to the shift amounts in the horizontal and vertical directions adjusted by the shift amount adjustment unit.