A computed tomographic (CT) apparatus and for a method of controlling the same are provided. The CT apparatus includes an X-ray scanner configured to divide X-rays penetrating a subject by energy bands, and capture scout images of the respective energy bands. The CT apparatus further includes an image processor configured to generate substance images of substances of the subject, based on the scout images, and a display configured to display a substance image of the substance images. The CT apparatus further includes an input interface configured to receive a scanning region for the displayed substance image.