Optical switching behavior of polymer azobenzene liquid crystal (LC) was investigated by the use of reflection-mode analysis. Intensity of reflected light from the interface between glass substrate and sample changed in 300 μs on pulse irradiation. This response time is similar to that observed in the low-molecular-weight LCs. On the other hand, we obtained a slower decay than that observed in the low-molecular-weight LCs. The slower decay in the polymer LC may be due to slower diffusion and reorientation processes which are characteristic of the reflection-mode analysis. In the polymer, photoresponsive moiety is linked to a main chain through a chemical bond and mobility of the mesogen is suppressed, which leads to the slower diffusion and reorientation processes becomes slow in the polymer LC.