A temperature measuring system includes a laser light source that emits optical pulses, an optical fiber, arranged to pass through a plurality of temperature measuring points, and input with the optical pulses, and a measuring device that detects back-scattering light output from the optical fiber and measures a temperature at the plurality of measuring points, to acquire measured temperature data. The measuring device computes corrected temperature data by varying a degree of averaging of the measured temperature data in a time direction, according to whether a time-sequential difference temperature data have a spatial correlation or a time correlation within a range that uses a target position of the optical fiber as a reference.