The Japanese standard rocks JB-1 and JG-1 are analyzed with the electron microprobe. The glass chips are prepared by direct fusion method by Nicholls (1974). Slight modifications of Nicholls' method for fusion temperature and preparation of rock powder give good results. Production of homogeneous glass chips needs fusion for 20 seconds at temperature 1500 to 1600℃ for basalt (JB-1) and 1800 to 1900℃ for granodiorite (JG-1). Very fine rock powder less than 10μm is preferable.