Provided are an integrated light guide plate and a lighting device including the same. Micro-sized engraved lenses are provided on one surface of a transparent substrate, coated with a reflector pattern having a visually unrecognizable size, such that dual-surface lighting is realized and the ratio between intensities of dual-surface lighting is adjusted without the addition of a reflector plate and a diffuser plate. The transparent substrate includes a first surface, a second surface, and third surfaces connecting the first surface and the second surface to each other, the second surface provided with a lens pattern including engraved lenses.