To provide an optical path switching element with simple conformation, high durability, low member cost and high S/N, a spatial optical modulator and a picture display device using the same.

The optical path switching element has an light incidence part 3 through a light guiding member, a reflection part 6 which reflects an incident light entered from the optical incidence part 3, and a light emission part 4 which emits the reflected light to outside as an emitted light via the light guiding member 1. A material 5 with a variable refractive index is enclosed in the optical path containing the reflection part 6, a signal is given to the material 5 with the variable refractive index according to information, and the refractive index is changed. At this moment, incident light changes the refractive index of the material 5 with variable refractive index by the signal in the range which is not totally reflected on a boundary of the light guiding member 1 and the material 5 with the variable refractive index. The material 5 with the variable refractive index comprises at least a material which contains a two-frequency drive liquid crystal. The two-frequency drive liquid crystal provides a high switching speed element due to high speed alignment movement.