An apparatus for insertion of a key therein substantially prevents foreign matter from entering into a key insertion hole, and even if foreign matter does enter into the key insertion hole, discharges the foreign matter therefrom. A shutter is provided within the key insertion hole so as to be movable along a direction of insertion of a key. The shutter is always urged by a compression coil spring toward an opening of the insertion hole. In a state in which no key is inserted in the insertion hole, the shutter is urged by the compression coil spring and closes the insertion hole. As a result, foreign matter such as dust or the like can be prevented from entering into the insertion hole. Further, the shutter is provided with a reflecting surface, and when no key is inserted in the insertion hole, the reflecting surface reflects light from a light source so as to illuminate the opening of the insertion hole. Thus, even if a region surrounding the opening of the insertion hole is dark, the opening can be visually confirmed and the key can be easily inserted into the insertion hole.