A new small solid launcher named Epsilon is currently under development in JAXA. The Epsilon launch vehicle is normally three stage rocket system and can be added an optional liquid propulsion system to the third stage for the missions requiring precision orbit insertion. The SRB-A motor boosting the H-IIA vehicle and the H-IIB vehicle will be shared as the first stage motor. Upper-stage motors are inherited from the fifth M-V launch vehicle, from the viewpoints of development cost reduction, performance increase, and advanced technology succession. The solid motor side jet (SMSJ) system, which is used for the roll control during the first stage powered flight and the three-axis control after the SRB-A burnout, will be newly developed based on the technology of the SMSJ for the M-V vehicle. A maiden flight of the first Epsilon is scheduled in the summer of 2013. A successive concept of the advanced propulsion technologies for next-gen Epsilon are also described in the present paper. There are many technical challenges, such as new propellants and mass reduction of nozzle liner, to be tackled with for the next couple of year. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.