To provide a novel nano thermometer which can be used for temperature measurement of a wide temperature range, in a micrometer size environment, and also to provided a method for producing the same.

The nano thermometer comprising a carbon nanotube filled with a continuous columnar gallium can measure environmental temperature by length change of the columnar gallium, and is produced by the method comprising mixing of Ge2O3 powder and carbon powder uniformly, and performs heat treatment for this mixed powder at a temperature range of 1200 to 1400°C under an inactive gas flow.