PURPOSE: To permit the printing of graduation line of scale of a desired unit of length on a printing medium tape by a method wherein a scale printer is provided with a scale data producing means, producing a dot pattern to print the graduation line of the scale of unit of length and supplying it to a printing buffer.

CONSTITUTION: Code data of letter and/or symbol, which are inputted from a key board 3, are stored into the text memory 41 of a RAM 40 as letter data. A plurality of printing format informations, such as the data of set letter sizes, data of type faces and/or the data of modification of selected letters and the like, are stored in a printing format memory 42. The unit of length of a set scale or cm, inch, feet, shaku and the like are stored in a scale unit memory 43. The value SL of total length of a set scale is stored in a scale length memory 44.