To provide a locking device to arrest shifting of a shelf board in vertical and lateral directions.

This shelf board device is erected by hooking back end hooks 16 of a bracket 14 into optional slits among many slits 12 bored on the front face of a support 10, then by fitting a shelf board 18 in the bracket 14. In this case, a locking device 30 for shelf board which is provided for fixing the shelf board 18 to be impossible to shift in vertical, lateral and longitudinal directions is equipped. The locking device 30 for shelf board is equipped with a fitting part 32 which is elastically fitted into the remaining gap between the top hook 16 and the slits 12 of the bracket 14, and an engagement part 34 to be fitted into an engagement hole of the back face of the shelf 18 which is protruded from and integrated with the fitting part 32.