[Problem] To provide an temperature measurement system and an abnormality detection method which are capable of detecting abnormality at an early stage, the abnormality occurring in a facility such as a chemical plant, an oil refinery plant, or a thermal power plant.
[Solving Means] A temperature measurement system includes an optical fiber 30, a temperature distribution measurement apparatus 31, and a data processing apparatus 32. The temperature distribution measurement apparatus 31 is configured to detect backscattered light by causing light to enter the optical fiber 30, and acquire the temperature distribution of the optical fiber 30 in the length direction thereof based on the result of the detection. The data processing apparatus 32 is configured to store therein the temperature distribution acquired by the temperature distribution measurement apparatus 31, perform signal processing on a difference temperature distribution obtained by computing the difference between a current temperature distribution and a past temperature distribution, and determine whether or not abnormality is present based on the result of the signal processing.