PURPOSE: To eliminate irregular density in outputting characters and diagrams caused by rise of temperature of a thermal head.

CONSTITUTION: A sublimation type hard copy device is provided with two look-up tables 11, 12 and a level detecting circuit 13. In the look-up table 11, correction data for printing temperature of a thermal head 5 is described and this correction data is for high density level. To the contrary, in the look-up table 12, correction data for printing temperature of the thermal head 5 is described and this correction data is for low density. The level detecting circuit 13 detects a density level indicated by a digital signal written in a memory 3 and outputs to a switch 14 a control signal for selecting the output of either of the look-up tables 11 and 12 in accordance with the detected density level.