To provide a device for attaching a light to a shelf board, by which the light is easily attached to the lower surface of a shelf board, and even to a ready-made shelf board only by adding a minimum process to the shelf board to add a useful lighting function without a big increase in cost.

The device is composed by attaching the light 9 to the lower surface of the shelf board 7 through attaching members 68. The shelf board is formed with channel-shaped reinforcement portions (46, 47, 48) at the front edge of a mounting board 45, is longitudinally provided with a reinforcement member 52 at the transverse intermediate part of the lower surface of the mounting board, and is locked with an attaching member across the channel-shaped reinforcement portion and the reinforcement member. The light is secured to the attaching members with screws from below. Specifically, a vertical surface 53 of the reinforcement member is formed with openings 67, the front end of the attaching member is formed with a downward locking piece 69 and an appreciate place at the intermediate part is formed with a screw hole 70, the rear end of the attaching member is inserted into the opening, its front end is locked to a lower board 47 and a raised piece 48, and the light is secured with screws by using the screw holes of both attaching members.