To provide a vehicular security system effectively preventing crimes such as breaking into a vehicle and vehicle theft by utilizing light shielding means for shielding against lights penetrating through a window glass.

The system is equipped with: the light shielding means 4, 5 for shielding against lights penetrating through the window glass of a vehicle; a vehicle abnormality detection means 2 for detecting abnormality of the vehicle due to the crimes such as breaking into the vehicle and vehicle theft; and crime prevention means 40, 50 for driving the light shielding means 4, 5 by driving devices 41, 51 for preventing the crimes according to the detected abnormality, when the abnormality is detected by the vehicle abnormality detection means 2.