A membrane reformer is a high efficient pure hydrogen production system composed of a steam reformer equipped with palladium-based alloy membrane modules for hydrogen separation in its catalyst bed, and performs steam reforming reaction of natural gas and hydrogen separation processes simultaneously, without shift converters and purification systems. The reforming process with simultaneous hydrogen separation is free from the limitation of chemical equilibrium and provides highly energy efficiency than conventional technologies. Due to these advantages, the membrane reformer is expected as on-site hydrogen generators including hydrogen refueling stations for fuel cell vehicles. We have so far developed and operated a 40 Nm³/h-class membrane reformer and demonstrated its high energy efficiency of 76% (HHV) and the product hydrogen was supplied to fuel cell vehicles. Its simple system configuration reduced the total volume of the system to 1/3 of conventional reforming system. In the present study, we are promoting development towards commercialization of the membrane reformer technology, focusing on further improvement of energy efficiency to produce hydrogen, proof of long-term durability and reliability, and establishment of system engineering technologies under The New Energy and Industrial Technology Development Organization (NEDO) 3-year program. We have successfully achieved the challenging target of the project: to develop a membrane reformer system that can produce 99.99% or higher-purity hydrogen from natural gas at a rate of 40 Nm³/h with hydrogen production energy efficiency of over 80%. This system is believed to give the highest efficiency in producing hydrogen from natural gas among various competing technologies.