A dorsal rib portion from the post-cranial skeleton of a small ornithischian dinosaur discovered from the fossiliferous locality in Boseong was analyzed through Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Electron Probe Microanalyser (EPMA), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) to determine the detailed microstructure and components of the fossilized dinosaur bone. The rib bone portion was specifically chosen as an initial research sample to establish efficient experimental methodology in order to apply to future dinosaur osteohistological study. Since the fossilized bone was highly compressed by the surrounding matrix, distinct features of bone tissues were not clearly visible in OM cross sections. Instead, we observed two other features: (1) numerous patches of calcite crystals in various orientations filling the void region;(2) apatite crystals of 10~200 nm size constituting the bone matrix region, which is revealed by XRD, EPMA, SEM, and TEM. The data we have obtained so far is preliminary to directly elucidate the specific microstructural properties of fossilized bone such as bone formation and growth patterns, but we have provided possibility of revealing the characteristic features of dinosaur bone microstructure in nano-scale and established efficient specimen preparation methods for correlative Optical Microscopy (OM)-Electron Microscopy (EM) study.