  We investigate gravitational lensing by a photon sphere in a
Reissner-Nordstr\"{o}m naked singularity spacetime in strong deflection limits.
Because of the nonexistence of an event horizon and the existence of a
potential barrier near an antiphoton sphere, infinite numbers of images
slightly inside and outside of a photon sphere can appear. We obtain the
analytic expressions of the factors of logarithmic divergent terms and the
constant terms of the deflection angles in the strong deflection limits not
only the for the little outside but also the barely inside of the photon sphere
without Taylor expansions in the power of an electric charge. We can
distinguish between a Reissner-Nordstr\"{o}m black hole spacetime and the naked
singularity spacetime since the images little inside of the photon sphere
around the naked singularity are significantly brighter than the image barely
outside of the photon sphere around the black hole and the naked singularity.
