Disclosed is a method for analyzing internal density of material by using X-ray computed tomography, comprising the steps of installing a cylinder-shaped jig between an x-ray generator and an x-ray detector, inserting a material to be analyzed and a plurality of standard specimens whose densities are known into the inside of the cylinder-shaped jig, performing X-ray computed tomography while rotating the cylinder-shaped jig through 360°, and calculating the internal density of distribution of the material to be analyzed by using the X-ray intensities shown in the x-ray tomography image. By using the method of the present invention, X-ray tomography image is converted to the image showing the internal density distribution of the material, improving the qualitative decision by naked eye by providing quantitative decision method.
