Japan Aerospace Exploration Agency (JAXA) started the 'Silent Supersonic Technology Demonstration Program' in 2006. In this program, JAXA is now pursuing R&D on supersonic technologies to improve not only economical efficiency but also environmental compatibility, and also planning the new flight demonstration project to validate the design tool and to demonstrate the low sonic boom technology. This paper describes the overview of this program and the current status of the R&D including the flight demonstrator design.