A pH-responsive nanoparticle made of a pH-responsive polymer and a poly(lactic-co-glycolic acid) by self-assembly includes a polyethylene glycol derivative and a R-Histidine derivative that are subjected to a chemical reaction to form the pH-responsive polymer, wherein the surface electric potential of the pH-responsive nanoparticle is −25 to 10 mV, such that when a pH value of the pH-responsive nanoparticle is changed from 7.4 to 5.0 depending upon an external environment, a surface zeta potential of the pH-responsive nanoparticle is converted from negative charge to positive charge.
