This paper describes the effects of thermophysical properties of printing papers on transient temperature response in the Direct Thermal Printers (DTP). DTP produces printed images by selectively heating thermal papers when a thermal head, which includes dot heaters, contacts thermal papers directly. The printing quality of DTPs is strongly dependent on thermophysical properties of thermal papers. Our study aims to optimize the printing process of DTPs in order to reduce power consumption of DTPs while maintaining printing quality. In this paper, a relationship between thermophysical properties, which are density, specific heat and thermal conductivity of the printing paper, and the transient temperature response of the paper was investigated quantitatively using 3-dimentional thermal conduction analysis. Through the analysis, we clarified the dominant factor in the temperature rise of the papers from the viewpoint of the thermophysical properties.