A light guide plate for a surface light-emitting device and a method of manufacturing the same are disclosed wherein the light guide plate is constructed in the form of an optical waveguide including an upper cladding film, core films formed with V-cut grooves, and a lower cladding film, so that since the upper and lower cladding films with a relatively low refractive index are respectively located on upper and lower surfaces of the core films, external foreign substances cannot penetrate into the core films, and the core films are not brought into contact with other components, whereby optical transmission properties are not changed and brightness can be also enhanced, and since the V-cut grooves are formed or both the V-cut grooves and optical waveguides are formed at the same time by means of a simple hot embossing process, the manufacturing costs can be saved.