PURPOSE: To automatically set a color ribbon without performing menu operation and to prevent the lowering of throughput and the excessive supply of ink due to erroneous operation.

CONSTITUTION: A head pin is allowed to impinge against a platen at a position where a monochromatic ribbon is mounted to measure the distance A between a printing head and a platen (st. 3) and, subsequently, the head pin is allowed to impinge against the platen at a position where a multicolor ribbon is mounted to measure the distance B between the printing head and the platen (st. 7). The difference C between the respective distances A, B is calculated (st. 9) to be compared with a boundary value α to judge the monochromatic ribbon or the multicolor ribbon (st. 11).