Thermally stable polyimide (PI), which has a photoreactive p-phenylenediacryloyl (PDA) moiety in the main chain with a rigid biphenyl as a side group, was prepared from a poly(amic acid) (PAA) solution using a thermal imidization process. PAA was synthesized successfully with a reasonably high molecular weight and gave high quality films with relatively good thermal stability. The photoreactions and photoalignments of PI were analyzed by ultraviolet-visible spectroscopy, and their liquid crystal (LC) alignment properties were examined. The PI in the film showed good photoreactivity to UV light irradiation. Linearly-polarized ultra-violet light (LPUVL) irradiation induced anisotropic reorientation of the polymer chains in the film due to a direction-selective photoreaction of the PDA moieties. All the films irradiated with LPUVL aligned the LCs in a direction perpendicular to the electric vector of the LPUVL. The pretilt angles of the LC molecules on the LPUVL irradiated film surfaces were controlled by the exposure dose of LPUVL and influenced by the thermal annealing history of the irradiated films. The LC alignments were retained on the films annealed at temperatures up to 210 degrees C.