The present invention relates to pH-sensitive carbon nanoparticles, a preparation method therefor, and drug delivery using same. pH-Sensitive carbon nanoparticles comprising imidazole are prepared and can mount a hydrophobic drug, a photosensitizer material, etc. thereon and allow drug release in a weak acid condition. Thus, the carbon nanoparticles can be used as a drug carrier for anticancer therapy, photodynamic therapy or light-mediated cancer immunotherapy.