  We investigate the superradiant instability of dyonic Reissner-Nordstr\"{o}m
(dRN) black holes with two charges under a charged massive scalar perturbation.
Two conditions for possessing a trapping well are obtained from analyzing
asymptotic scalar potential and far-region wave functions. It is clear that the
superradiant instability is not allowed in the dRN black holes because the
conditions for a trapping well are not compatible with the superradiance
condition.
