VEHICLE CABIN INTERIOR LIGHTING DEVICE

There is provided a vehicle cabin interior lighting device including: a light source that emits light; a polarizing member that converts the emitted light into p-polarized light; and a projection portion that is provided at an upper portion of an instrument panel, and onto which the p-polarized light is projected, and that reflects the projected p-polarized light without changing its polarization characteristics, and that causes the projected p-polarized light to be incident on a front windshield glass at Brewster's angle.