© Published under licence by IOP Publishing Ltd. The sub-micron spatial distribution of chemical states of carbon fiber (CF) and the interface between CF and resin must affect physical properties of carbon-fiber-reinforced plastic (CFRP). In order to evaluate scanning transmission X-ray microscopy (STXM) techniques for application to the chemical-state analysis of CFRP, we performed STXM measurements near C K-edge energies. The results of the spectral deconvolution analysis suggest the presence of another phase at the interface of CF and resin, which may be a coating layer. In addition, the preferred orientation of the stuck of graphene sheets to the fiber axis direction of CF was observed by using linear polarized X-ray beams.