An in-vehicle illuminating device capable of preventing light emitted from a light source from coming directly into a passenger's sight. An in-vehicle illuminating device 1 includes a housing 2, a reflective member 18 provided within the housing 2, a light source or LEDs 10 orienting a light axis of light emitted therefrom to the reflective member 18. Reflected light obtained by allowing the reflective member 18 to reflect the light emitted from the LEDs 40 is irradiated to the outside of the housing 2, thus preventing light emitted from the LEDs 40 from coming directly into a passenger's sight.