To make improvable the refrangibility of a birefringence plate which is provided with a vapor-deposited film, obliquely vapor deposited on a substrate surface and is birefringent, and an impregnated layer formed and impregnated in a columnar structure of the vapor-deposited film without increasing the film thickness.

The birefringence plate 1 is provided with a birefringent vapor- deposited film 3 formed by obliquely vapor depositing tantalum pentoxide and an impregnated layer 4 composed of polydiacetylene impregnated in gaps 3a of the columnar structure, polymerized and hardened. As the impregnated layer 4 is formed using a molecular orienting organic material, the refrangibility of the birefringence plate is improved without increasing the film thickness.