This study investigated the effects of red and blue LED light on mushroom growth to establish the optimum artificiallighting method for Pleurotus eryngii in a closed mushroom-factory system. Fresh weight, height, width, pileus chromaticity, and pileus hardness were measured to evaluate the effects of LED lighting on mushroom growth and quality. During cultivation, the humidity, temperature, and CO2 concentration were maintained above 90±5%, at 14–16oC, and at 1,000–1,500 ppm, respectively. Fresh weight and height were greater under red (650 nm, 74.3 μmol m⁻2 s⁻1) and green LED light (525 nm, 87.4 μmol m⁻2 s⁻1) than under blue LED light (450 nm, 108.0 μmol m⁻2 s⁻1). Red LED light at a photosynthetic photon flux density of 74.3 μmol m⁻2 s⁻1, applied in a 1-h on/off cycle, resulted in a marketable yield of 150 g. This represented a 13.6% increase over the control yield of 132 g under fluorescent lighting. The stipe length was 7.1 cm under blue light, which was shorter than the 9.6 cm recorded under red light.