The cathodoluminescence microscope, model TCL-1, equiped with a monochrometer and a highly sensitive photon-counter for spectral analysis, is devised and described. Both normal optical image and cathodoluminescence image on the same polished thin section are able to be observed alternately with the microscope. On the preliminary study, we observed the cathodoluminescence of quartz and carbonates of variable occurrences and measured the spectra. The cathodoluminescence microscope is very useful for sedimentary petrological studies, e. g., provenance of sandstone, cementation and pore structure of reservoir rocks, etc.