Disclosed is a method for restoring a scan image. The method includes the steps of: measuring a blurring function oversampled with respect to a slit image obtained through a slit inclined at a predetermined angle in a vertical or horizontal direction according to the predetermined angle; and restoring a scan image to increase a resolution of an interface of a subject in the scan image obtained by obtaining the subject using the measured blurring function. Computed tomography (CT) that applies image restoration by increasing sampling can secure a precise image for computer-aided design (CAD)/computer-aided manufacturing (CAM) additionally used in a system used when actually diagnosing a patient, and thus does not require additional expenses and equipment.