A membrane reformer is composed of a steam reformer equipped with palladium-based alloy modules in its catalyst bed, and can perform steam reforming reaction and hydrogen separation processes simultaneously, without shift converters and purification systems. It thus can be configured much more compactly and can provide much higher efficiency than the conventional technologies. We have manufactured and tested a world-largest scale membrane reformer with a rated hydrogen production capacity of 40 Nm3/h. The operation test has successfully been proceeding for over 3,000 hours in one of the hydrogen refueling stations in Tokyo, which has demonstrated the potential advantages of the membrane reformer: simple system configuration as benefited by single-step production of high-purity (99.999% level) hydrogen from natural gas, compactness and energy efficiency as high as 70 to 76% under both the rated and partial-load operating conditions. The system has thus been proved to give the highest efficiency in producing hydrogen from natural gas among various competing technologies. The paper will present the latest achievements and the future plan of the membrane reformer technology development.