PURPOSE: To keep the color quality of a color ribbon itself and to enhance the durability of said color ribbon, by a method wherein a plurality of color ribbons are parallelly received in the case of a ribbon cassette freely detachable with respect to a printer body and only one color ribbon to be printed is fed by a ribbon converting mechanism part.

CONSTITUTION: A ribbon converting mechanism part 7 is constituted so that a crank leer 9 is oscillated in connection with the revolution of a rotary disc 8 rotating by the input of the electric signal from a control unit and the engaging end part of the crank lever 9 moves in an up-and-down direction during the stroke corresponding to one revolution of the rotary disc 8 and either one of objective black ribbon 2 W a blue ribbon 5 performing printing is located at the corresponding position of a printing head 6. The feed means of each color ribbon is controlled so that the output shaft 11a of a ribbon feed motor 11 is engaged with each of the torque pieces 10 corresponding to the black ribbon 2 W the blue ribbon 5 mounted in the cassette case 1 to feed only the color ribbon being selected.