Anti-ferroelectric liquid crystal cells mixed with one of dyestuffs of o ・ nitro ・ p ・ chloroaniline, acid brown M, acid red, azo blue, alizarin yellow R, chrome yellow, sudan I, sudan IV, fast violet B and brilliant yellow investigated on the photo-electromotive force and the theoretical analysis. The photo-electromotive force by the illumination strength of 1000 lux on the incident light of fluorescent lamp was measured. The photoelecctromotive force increased on the thin film cells compared with the thick and on the wafer having the low resistivity compared with the high. The photo-electromotive force had the highest value on the acid brow M cell among all cells. The theory of the photo-voltaic effect was considered because of establishment of the principle.