A temperature distribution measuring apparatus comprising: a bias signal applier configured to apply a bias signal having a frequency to a sample for a change in reflectivity of a reflection signal reflected from the sample; a scanner configured to scan the sample based on a first control signal indicating a start and an end of an image and a second control signal indicating a start and an end of a row or a column of the image; a detector configured to detect, from the reflection signal, a signal of interest reflected from a region of interest of the sample; and a controller configured to: convert the signal of interest into a frequency domain signal, extract a direct current component and a frequency component corresponding to the frequency of the bias signal from the frequency domain signal by filtering the frequency domain signal, calculate a relative amount of change in reflectivity of the sample using the extracted frequency component and the extracted direct current component, determine a pixel value of the image as the relative amount of change in reflectivity, and acquire a thermal image of the sample, wherein the detector comprises a pinhole , and wherein the signal of interest passes the pinhole , and remaining signals of the reflection signal do not pass the pinhole , and wherein said acquiring of said thermal image comprises two-dimensionally arranging the pixel value based on the first control signal and the second control signal. a bias signal applier configured to apply a bias signal having a frequency to a sample for a change in reflectivity of a reflection signal reflected from the sample; a scanner configured to scan the sample based on a first control signal indicating a start and an end of an image and a second control signal indicating a start and an end of a row or a column of the image; a detector configured to detect, from the reflection signal, a signal of interest reflected from a region of interest of the sample; and a controller configured to: convert the signal of interest into a frequency domain signal, extract a direct current component and a frequency component corresponding to the frequency of the bias signal from the frequency domain signal by filtering the frequency domain signal, calculate a relative amount of change in reflectivity of the sample using the extracted frequency component and the extracted direct current component, determine a pixel value of the image as the relative amount of change in reflectivity, and acquire a thermal image of the sample, wherein the detector comprises a pinhole , and wherein the signal of interest passes the pinhole , and remaining signals of the reflection signal do not pass the pinhole , and wherein said acquiring of said thermal image comprises two-dimensionally arranging the pixel value based on the first control signal and the second control signal. convert the signal of interest into a frequency domain signal, extract a direct current component and a frequency component corresponding to the frequency of the bias signal from the frequency domain signal by filtering the frequency domain signal, calculate a relative amount of change in reflectivity of the sample using the extracted frequency component and the extracted direct current component, determine a pixel value of the image as the relative amount of change in reflectivity, and acquire a thermal image of the sample, wherein the detector comprises a pinhole , and wherein the signal of interest passes the pinhole , and remaining signals of the reflection signal do not pass the pinhole , and wherein said acquiring of said thermal image comprises two-dimensionally arranging the pixel value based on the first control signal and the second control signal. <EOS>