In order to improve productive efficiency of plant factory because the vegetable price of plant factory is high, in this study, leaf lettuce (Early impulse) was employed as specimen in plant factory and root of the lettuce was applied various PEFs for increasing lettuce growth rate. The experimental results showed PEF intensity from 0.2 to 1.0 kV/cm was occurred to growth stimulation. On the contrary, over 1.0 kV/cm was occurred to growth inhibition. Furthermore, the roots of increased leaves weight were lead to more growth than the roots of decreased one. It was suggested that PEF application have a positive effect on the root cells. On the other hand, analysis results of liquid fertilizer showed no significant difference between prior to and after application with PEF. The result suggests that PEF does not affect the composition of liquid fertilizer but directly influence the growth of lettuce in this study.