The solid-liquid phase transition was examined for aqueous dispersions of highly monodisperse charged-polystyrene latex having various surface charge densities. The phase diagram was determined using the volume fraction of the particle, the surface charge density of the particle, and the salt concentration as experimental variables. With increasing charge density, the liquid state first became a solid state, and then a reentrant solid-to-liquid phase transition was observed. The reentrant transition with increasing charge density has been previously reported for dispersions of ionic silica, which have relatively large particle-size polydispersity. The solid regions for the present latex were much larger than those for the silica system. The present study implies universality of the reentrant phase transition in charged colloidal systems, although the particle-size polydispersity affects the phase behavior in a quantitative manner. The reentrant transition could not be explained by the numerical simulation based on the Yukawa potential and renormalized charge concept.