A computed tomography (CT) apparatus includes a reconstruction unit which reconstructs a first CT image corresponding to a field of view (FOV) by using a first sinogram acquired by a CT scan of an object; and a correction unit which acquires a second sinogram by performing forward projection on the first CT image and acquires a second CT image by using the second sinogram and a third sinogram representing a portion of the object that is not included in the FOV. Thus, the CT apparatus reduces generation of image errors to thereby provide a high-quality reconstructed CT image.