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.