Edge enhancement is an important image processing in imaging systems. When the enhancement is insufficient, we feel the image is out of focus, but when it is too strong, we feel unnatural. So, the optimum degree of the edge enhancement is investigated by using subjective evaluation. Several types of image are prepared by digital still camera (D1, Nikon). The image capturing conditions are no edge enhancement, no image data compression and taking care of low noise. The edge enhancement is carried out on adjusting neighboring 4 pixels according to Laplacian operation. The degree of the edge enhancement is adjusted by controlling the intensity of Laplacian operation. In every images, the image quality is improved by certain degree of edge enhancement. It is observed that the optimum degree of edge enhancement shows difference among the categories of images.