PURPOSE: To obtain proper printing quality by retracting a printing head from a predetermined printing position so as to allow an ink ribbon to be shifted smoothly and completely when actuating a ribbon-shifting mechanism for transversely shifting an ink ribbon.

CONSTITUTION: When ribbon shifting data are fed into a CPU 17 from a host computer during the operation of a printer, the CPU 17 first cuts off driving circuits 21W24 to thereby stop a printing operation. The CPU 17 then actuates a stepping motor 20 so as to retract a printing head 17 and a paper guide 15 together with a carrier 5. This serves to widen the gap between the printing head 7 and a platen 14, and the travelling path of an ink ribbon IL is thereby widened. Thus, any risk of the ink ribbon IL being caught by the printing head 7 and a ribbon mask 16 can be eliminated, whereby a smooth shifting operation is attained.