Disclosed are a light guide plate, a front illumination type liquid crystal display device using the same, and a method for displaying an image therein. A light reflection pattern is formed on a light reflection surface of the light guide plate so as to change an optical distribution and prevent the moire phenomenon. The light reflection pattern prevents the light from being leaked through a side of the light guide plate, so an effective display area is not divided into a bright area, a boundary area, and a dark area. It is possible to change the optical distribution and to prevent the moire phenomenon, so the liquid crystal display device can display an image with an improved brightness uniformity.