Disclosed are a composition including hydrophilic nanoparticles that have a monosaccharide-phosphate or a derivative thereof adhered to the surface thereof, a colloidal solution of the composition dispersed in water, and a magnetic resonance imaging contrast agent including the colloidal solution. According to the present invention, nanoparticles having biocompatibility and excellent water-dispersibility can be prepared by modifying the surface of inorganic nanoparticles. The prepared nanoparticles may be effectively used in a variety of applications including, for example, in vivo imaging applications. such as an MRI contrast agent, nano-electronic convergence technologies such as a quantum dot light emitting device, biomedical applications such as hyperthermia, or the like. Moreover, compared to existing nanoparticles dispersed by a dispersion stabilizer known in the art, excellent dispersion stability and a relatively small hydrodynamic diameter may be attained.