An optical coherence tomographic device comprising: a light source; a measurement light generator configured to generate measurement light by using light from the light source and to generate reflected light from a target region in a scattering sample by irradiating the target region with the measurement light, the target region comprises a blood vessel; a reference light generator configured to generate reference light by using the light from the light source; an interference light generator configured to generate interference light by combining the reflected light from the target region generated in the measurement light generator and the reference light generated in the reference light generator; an interference light detector configured to detect the interference light generated in the interference light generator and to generate interference signals by converting the interference light; a processor; and a memory storing computer-readable instructions therein, characterized in that the computer-readable instructions, when executed by the processor, causing the optical coherence tomographic device to execute: acquiring a plurality of tomographic images for a same cross section in the target region in time series from the interference signals generated in the interference light detector; calculating an entropy of the generated interference signals based on the plurality of tomographic images acquired in time series; calculating an entropy of noise component in the generated interference signals based on the plurality of tomographic images acquired in time series; and correcting the entropy of the generated interference signals by subtracting the entropy of noise component from the entropy of the generated interference signals, specifying a dynamic part in the tomographic images based on the corrected entropy of the generated interference signals; wherein the dynamic part is the blood vessel comprised by the target region. a light source; a measurement light generator configured to generate measurement light by using light from the light source and to generate reflected light from a target region in a scattering sample by irradiating the target region with the measurement light, the target region comprises a blood vessel; a reference light generator configured to generate reference light by using the light from the light source; an interference light generator configured to generate interference light by combining the reflected light from the target region generated in the measurement light generator and the reference light generated in the reference light generator; an interference light detector configured to detect the interference light generated in the interference light generator and to generate interference signals by converting the interference light; a processor; and a memory storing computer-readable instructions therein, characterized in that the computer-readable instructions, when executed by the processor, causing the optical coherence tomographic device to execute: acquiring a plurality of tomographic images for a same cross section in the target region in time series from the interference signals generated in the interference light detector; calculating an entropy of the generated interference signals based on the plurality of tomographic images acquired in time series; calculating an entropy of noise component in the generated interference signals based on the plurality of tomographic images acquired in time series; and correcting the entropy of the generated interference signals by subtracting the entropy of noise component from the entropy of the generated interference signals, specifying a dynamic part in the tomographic images based on the corrected entropy of the generated interference signals; wherein the dynamic part is the blood vessel comprised by the target region. acquiring a plurality of tomographic images for a same cross section in the target region in time series from the interference signals generated in the interference light detector; calculating an entropy of the generated interference signals based on the plurality of tomographic images acquired in time series; calculating an entropy of noise component in the generated interference signals based on the plurality of tomographic images acquired in time series; and correcting the entropy of the generated interference signals by subtracting the entropy of noise component from the entropy of the generated interference signals, specifying a dynamic part in the tomographic images based on the corrected entropy of the generated interference signals; wherein the dynamic part is the blood vessel comprised by the target region.