To facilitate formation of a shelf board which can effectively display merchandise and facilitate shape change from a standard rectangular shelf board by supporting a shelf board for disposing merchandise by brackets and detachably forming a sector auxiliary shelf board with a curvedly-protruding front center along the front edge of the shelf board.

An auxiliary shelf board 21 dechatably mounted to a shelf board 1 has a rear edge 22 formed in a straight line corresponding to the front edge member 2a of the shelf body 2, a front face 23 with a center part formed in a curvedly-protruding sector, and comprises a sector shelf member 24, a curved front edge member 26 provided along the front edge, and a front lace 27. The front edge member 26 protrudes higher than the shelf board member 24, acting as a fence. The auxiliary shelf board 21 is mounted to the front edge of the shelf board 1 by removing the fence or the like on the front edge of the shelf board 1, and by pinching and fixing the rear edge member 25 and the front member 2a with connecting members 31, while abutting the rear edge member 25 of the auxiliary shelf board 21 on the front edge member 2a of the shelf board body 2.