PURPOSE: To make printing quality good within a broad temperature range by a method wherein a reduction rate of an applicable energy due to self heating of a thermal head itself is made less than a reduction rate of applicable energy due to rise of ambient temperature within a specified temperature range.

CONSTITUTION: A first thermosensitive element 11 for detecting temperature of a base material or a heat slinger of a thermal head 1 and a second thermosensitive element 2 for detecting ambient temperature of the thermal head are provided. A first control means for controlling an applicable energy to a heating element 12 based on variation in temperature of the first thermosensitive element 1 and a second control means for controlling applicable energy to a heating element 1a based on variation in temperature of the second thermosensitive element 12 are established. A relation between a reduction rate (p) of an applicable energy to rise in temperature of a thermal head 1 by the first control means to a reduction rate (q) of an applicable energy to rise in temperature of ambient temperature of the thermal head 1 by the second control means satisfies a relation of p<q near the ambient temperature of the thermal head, and its temperature range has a range of, at least, 20°C or over by taking the ambient temperature as a start point.