Possibility of a completely-controlled plant factory using red laser diodes and light-emitting diodes is discussed and basic experimental data concerning relative growth rate, photosynthetic rate and vitamin C contents are given for lettuces under these lights. Special attention is given for the promotion of growth per unit radiation energy under intermittent (pulsed) application of lights. Plant factories using these diodes may be materialized in near future if the price of laser diodes is reduced and suitable intermittent lights are applied.