A fastening device connects two wall parts of a furniture part, in particular a rear wall to a side wall of a drawer. The fastening device has at least one locking projection resilient about an imaginary spring axis on one wall part, which locking projection can be locked—preferably detachably—into a locking receptacle fastened to or formed on the other wall part. The imaginary spring axis of the locking projection is at an angle—preferably substantially at a right angle—from a wall of the wallpart. The locking receptacle is formed on the other wall part as an opening, and an imaginary normal on the opening is substantially parallel to the imaginary spring axis of the resilient locking projection.