Manipulation of light using nanostructures is not only essential for the high integration of optical devices, but also a key to utilizing the quantum nature of light and creating high performance optoelectronics devices. We are focusing on electron microscopy, offering structural characterization at the atomic level, and particularly on EELS and CL, providing direct access to electronic states and optical functions. By combining nanoscale optical measurements and electron beam processes, we precisely and freely control the positional relationship among nano-optical materials and structures to maximize their synergy, thereby developing next-generation optical devices.