Temperature sensor and temperature measuring device

A temperature sensor comprising:

• a pair of thermocouple wires made of respective metallic materials different from each other;
• a temperature measuring junction formed by joining tip ends of the pair of thermocouple wires together;
• an outer tube made of a metallic material and having a tip end and a base end, the tip end holding the temperature measuring junction therein or having a tip end cover mounted thereto in which the temperature measuring junction is held, the base end allowing the pair of thermocouple wires to protrude therefrom;
• an insulator made of an insulating material and disposed in the outer tube to insulate the pair of thermocouple wires from the outer tube and fix the pair of thermocouple wires to the outer tube;
• and
• a glass seal made of a glass material and filled in at least either of the base end of the outer tube or a holder mounted to the base end of the outer tube to seal the outer tube, wherein
• the pair of thermocouple wires disposed in the outer tube have surfaces where passive films are respectively formed on the surfaces of the pair of thermocouple wires due to oxidization of the metallic materials,
• the pair of thermocouple wires from an N-type thermocouple;
• the pair of thermocouple wires include a positive-leg thermocouple wire comprising Ni, Cr and Si;
• the pair of thermocouple wires include a negative-leg thermocouple wire comprising Ni and Si;
• the passive film formed on the surface of the positive-leg thermocouple wire comprises Cr-oxide or Ni-oxide at a highest content;
• and
• the passive film formed on the surface of the negative-leg thermocouple wire comprises Ni-oxide at a highest content.