  We examine the stability of extremal braneworld Reissner-Nordstr\"{o}m black
holes under massive charged scalar perturbations. We show that similar to the
four-dimensional case, the superradiant amplification can occur in braneworld
charged holes. More interestingly we find that when the spacetime dimension is
higher than four, a trapping potential well can emerge outside the braneworld
black hole. This potential well is the extra dimensional effect and does not
exist in four dimensions. It triggers the superradiant instability of the
extremal braneworld charged holes.
