Provided is an in-vehicle interior illuminating device which is strong against vibration, high/low temperatures, tensile load and the like with excellent contact reliability, and furthermore, has small sizes. The device is provided with a design section (10), and a functional component (20) arranged on the outer side of the chamber of the design section (10). The functional component (20) has a functional component main body (21), which has a switch section (24), a lamp mounting section (25) and a terminal exposing section (21a) having exposed therefrom a plurality of crimping terminals (27), which are electrically connected to the switch section (24) and the lamp mounting section (25). The functional component also has a protection cover (30) which is assembled to the functional component main body (21) so as to cover the terminal exposing section (21a). The protection cover (30) is provided with a connector (32) which fits in a connector (40) on the side of a wire harness (WH). The connector (32) is composed of a connector housing section (33) integrally formed with the protection cover (30), and a plurality of terminals (34) which are fixed to the protection cover (30) and are fitted in the crimping terminals (27), respectively, in the step of assembling the protection cover (30) to the functional component main body (21).