To provide an interior lighting system for a vehicle capable of reducing the power consumption, elongating the service life, and improving the reliability in wiring by reducing the man-hours in assembling.

This interior lighting system comprises a light emitting element loaded substrate 14 loading a light emitting diode 13, a light emitting element case 15 provided with a light emitting window 21 capable of outwardly transmitting the light, and fixed to the light emitting element loaded substrate 14 to accommodate the light emitting diode 13, and a harness connecting part 12 press-fitted with a terminal of a wire harness 11 connected to an electric circuit at a car body side, and fixed to the light emitting element loaded substrate 14. By this constitution, the power consumption of a power source can be reduced, the life of the power source can be elongated, and the reliability in wiring can be improved by reducing the man-hours in assembling.