The present invention has for its object to provide a composition in which a photoluminescent carbon nanoparticle having no dependency of an emission wavelength on an excitation wavelength and being enhanced in terms of quantum efficiency is dispersed, a process of producing the same, and an application of the same. The composition of the invention has a photoluminescent carbon nanoparticle dispersed in a water-soluble solvent. The photoluminescent carbon nanoparticle contains a carbon atom, an oxygen atom, a nitrogen atom, and a hydrogen atom if required. As shown in FIG. 6, the photoluminescent carbon nanoparticle has an intensity of a C—N bond and/or C—O bond-derived peak (285.98 eV) larger than that of a C—C bond and/or C—H bond-derived peak (284.95 eV) in terms of X-ray photoelectron spectroscopic spectra, and a Raman spectrum having a peak based on a G-band and a D-band.