[Object] To provide a temperature distribution measurement apparatus and a temperature distribution measurement method capable of easily setting an appropriate transfer function in response to a change in the entire length of an optical fiber. [Solving Means] A temperature distribution measurement apparatus 20 includes a laser light source 21 optically connected to an optical fiber 24, a photodetector 26 configured to detect light backscattered in the optical fiber 24, and a temperature distribution measurement unit 27 configured to obtain a true measured temperature distribution by performing correction calculation using a transfer function on a temporary measured temperature distribution obtained based on an output from the photodetector 26. The temperature distribution measurement unit 27 stores therein data on a transfer function set for each entire length of the optical fiber 24 and for each longitudinal position in the optical fiber 24. Then, when the length of the optical fiber 24 is changed, the temperature distribution measurement unit 27 changes the transfer function to be used in the correction calculation by using the data on the transfer function.