PURPOSE: To obtain more legible prints with higher speeds than the conventional recorders by a method in which the speed of a carriage is switched to a speed corresponding to a shorter electrifying period than electrifying periods necessary for keeping printing quality normal.

CONSTITUTION: Electrifying STB width to a thermal recording head 1A is set to a shorter time T3 than a time T1 on the usual printing mode by a high-speed printing mode command, and the electrifying period is set to a shorter period T4 than the usual period T2, Pulse rate to the carriage pulse motor 7 is switched to T2/T4 timse correspondingly to shortened electrifying periods, and main routine is restored to make high-speed printing.