A nondestructive identification device includes: a radiation source 1 irradiating an x-ray 2 to a standard sample 5 made of a known material and a sample 3; a sensor 4 detecting a radiation ray having transmitted the standard sample 5 and the sample 3; a signal processing device 7 converting a signal of the sensor 4 into an image; an image processing device 8 which performs adjustment on an entire second image to make a luminance value of a part of the standard sample 5 in the obtained image or a relation between the luminance value and a thickness of the standard sample 5 in a first image where the energy of the radiation source 1 is first energy be the same as that in the second image where the energy of the radiation source 1 is second energy, and which performs a computation processing to take a difference or a ratio between the adjusted second image and the first image; and a display device 9 displaying an image.