Temperature measuring device and temperature measuring method

A temperature measuring method performed by a temperature measuring device having a non-transitory computer-readable medium storing computer-readable instructions that, when executed by a hardware-processor, causes the hardware-processor to generate temperature calculations of an optical fiber, the computer-readable medium, comprising:

• an acquisition step of acquiring spectrum data that indicates a spectrum of Brillouin scattered light generated by causing light to be incident on an optical fiber;
• an analysis step of analyzing the spectrum data and obtaining a Brillouin frequency shift amount;
• a correction step of predicting an amount of change in the Brillouin frequency shift amount due to structural relaxation of the optical fiber from a thermal history of the optical fiber, and correcting the Brillouin frequency shift amount obtained in the analysis step using the predicted amount of change;
• and
• a temperature calculation step of obtaining a temperature of the optical fiber on the basis of the Brillouin frequency shift amount corrected in the correction step.