Three chiral azobenzene compounds were prepared. A cholesteric phase was induced by mixing the chiral azobenzene compounds in a host nematic LC. A twising power of the three chiral azobenzene compounds was depended on the distance between azobenzene moiety and chiral moiety. The twisting power of the chiral azobenzene compounds was decreased by UV irradiation to cause trans to cis photoisomerization of the azobenzene compounds. Next, a compesated nematic phase was induced by mixing of a chiral dopant and a chiral azobenzene compound in the host nematic LC. The transmittance of the compesated nematic LC was drecreased by the UV irradiation, and restored by Vis irradiation. The reversible change in the transmittance can be interpreted in terms of the photochemical phase transition between the compesated nematic and the cholesteric phases.