One LED is used as an LED light source mechanism that illuminates an illumination surface, the illumination surface being laterally long and wide in a left/right direction, in which a central axis of the LED is disposed at a position on a center line vertically extending from a central part in the left-right direction of the illumination surface in such a manner that the LED faces the illumination surface, and two reflection surfaces are formed in a conical shape on a reflection surface forming place so as to surround the illumination surface, a light guide part, and the LED, and a center line of the conical shape is disposed on the central axis of the LED, the two reflection surfaces being configured to reflect light that is emitted from the LED toward an outside of the illumination surface.