To provide an OFDR device and an OFDR method capable of measuring a large strain distribution or a large temperature distribution within a narrow measured wavelength range by using an FBG. A measured optical fiber 13 includes a plurality of gratings that is overlappingly formed in order to reflect a plurality of different wavelengths. An OFDR device 1 measures a strain distribution or a temperature distribution of the measured optical fiber 13 on the basis of the result of detection by a measuring range non-inclusion detector 26 that detects gratings of the plurality of gratings of which the reflected wavelengths are not included in the measured wavelength range from the peak wavelengths detected by a peak wavelength detector on the basis of measured wavelength range non-inclusion detecting condition data (Ds) in which a predetermined measured wavelength range is set in the direction of the axis of the peak wavelengths.
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