A computed tomography (CT) apparatus includes an X-ray source configured to generate X-rays; and a detector which is configured to detect the X-rays radiated by the X-ray source, and includes a counting detection region configured to generate X-ray data corresponding to the detected X-rays according to a photon counting method, and an integrative detection region which is configured to generate the X-ray data corresponding to the detected X-rays according to a charge integration method, and is formed on an outer portion of the counting detection region with respect to a rotation axis of a gantry.