Abstract: A reversible heat-sensitive layer 1a provided with an electron donative precursor and a reversible developer that colors and discolors the precursor, is provided on the surface of a base, and the reversible heat-sensitive recording layer is heated previously to a molten state and then quickly cooled to a solid colored state. Using this reversible heat-sensitive paper (reversible writing heat-sensitive paper), the reversible heat-sensitive recording layer is heated during operation to a color-erasing temperature range lower than the melting temperature of the layer, thereby, a heated part is discolored and written with information. Thus, the life of the reversible heat-sensitive layer can be prolonged and information can be written with weak light.

Abstract: A temperature indicating display device capable of displaying a thermo-history above a predetermined temperature reliably and irreversibly. Moreover, it is possible to provide a laminated body having a temperature detecting layer and an information recording film layer. When the temperature indicating display device is exposed to a predetermined temperature, an irreversible shift is caused and the temperature history can be displayed. Moreover, the temperature indicating display device includes an information recording film layer containing information, an information record holding layer for holding the information, and a temperature detection agent layer composed of a material whose state is shifted according to a temperature and is characterized in that when a predetermined temperature is detected, the material of the temperature detection agent layer is changed so as to change the display state of information recorded in the information recording layer.