A thermometer includes a protective structure and a tip member with a thermal contact surface secured to the protective structure. A heat conductive layer includes a sensing portion disposed in the tip member and a temperature indication portion disposed in the protective structure. A structure with temperature indication markings is laid out along the temperature indication portion. A reversible temperature-sensitive color changing layer is formed on the temperature indication portion to overlap the structure of the temperature indication markings, in which the sensing portion is adapted for sensing the thermal contact surface to conduct heat flow to the reversible temperature-sensitive color changing layer, producing a sensed temperature and a color changing zone of the reversible temperature-sensitive color changing layer in response to the sensed temperature thereby exhibiting a corresponding temperature value.