Projection of computer graphics images on walls or architecture, known as projection mapping, has been used widely and applied in many fields. In projection mapping, the relative alignment between the projected images and the target is important because the efficiency of projection mapping may be reduced due to misregistration. However, the process of alignment is manual and time-consuming. To solve this problem, we propose an automatic alignment method that uses depth information and geometrical characteristics of a plane. This method enables the correction of a distorted image projected from an arbitrary angle. As a result, distortion is reduced by applying our proposed method, which is evaluated by the error rate defined. Performing additional experiments and evaluating the effect of our method will be a part of our future works.